AIR BRAKE 





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THE AIR-BRAKE 



A PRACTICAL PRESENTATION OF THE MODERN DEVELOPMENTS 

OF THE AIR-BRAKE FOR STEAM AND ELECTRIC 

RAILROAD TRAINS 



By LLEWELLYN V. LUDY, M. E. 

PROFESSOR OF EXPERIMENTAL ENGINEERING, PURDUE UNIVERSITY. 
AMERICAN SOCIETY OF MECHANICAL ENGINEERS 



ILLUSTRATED 



CHICAGO 
AMERICAN SCHOOL OF CORRESPONDENCE 
1913 



5b 



Copyright, 1911, 1913 by 
American School of Correspondence 



Copyrighted in Great Britain 
All Rights Reserved 




©CI.A350138 
*4( 



CONTENTS 



PAGE 

Introduction 1 

Early forms of brake 1 

Interchangeable brake system 5 

Westinghouse air-brake 7 

Operation 11 

Westinghouse nine and one-half inch air-pump 11 

Eight and one-half inch cross compound 13 

Main reservoir 15 

Air-pump governor 16 

Engineer's brake valve 17 

Slide-valve and feed-valve 22 

Quick-action triple valve 25 

Plain triple valve 27 

Combined freight-car cylinder, reservoir, and triple valve. . 29 

Pressure-retaining valve 30 

High-speed brake 31 

Westinghouse "E T" locomotive brake equipment 33 

Manipulation 36 

Distributing valve 38 

Automatic brake-valve 48 

Independent brake-valve 53 

Reducing valve 55 

Pump-governor 55 

Westinghouse type "K" triple valve 56 

New York air brake system 65 

Air-pump 65 

Engineer's brake valve 68 

Quick action triple valve 71 

Foundation brake-gear 73 

Leverage 75 

Automatic slack-adjuster , 78 

Locomotive-driver brakes 80 

Locomotive-truck brake. . 82 

Westinghouse train air-signal system 83 



CONTENTS 



PAGE 



Special instructions in use and care of air-brake equipment. . . 86 

Train inspection 86 

Running test 86 

Service applications 86 

Emergency applications 87 

Use of sand 87 

Pressure-retaining valve 87 

Backing up trains 88 

Double-heading 88 

Conductor's brake-valve 88 

Use of angle-cocks 88 

Cutting out brakes 88 

Air-pump 89 

Engineer's brake valve 89 

Triple valve and brake-cylinders 89 

Air-brakes as applied to electric cars 90 

Westinghouse straight air-brake 91 

Air-compressor 95 

Pump governor 97 

Reservoir 101 

Brake-cylinder 101 

Operating valve 102 

Piping 106 

Safety-valve 106 

Westinghouse automatic friction-brake 108 

Train air-signal •. 109 

Stopping a car 110 




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INTRODUCTION 

"\V7HEN George Westinghouse in 1869 invented the air-brake 
and thereby enormously increased the possibilities of con- 
trol of railroad trains, he removed one of the most effective bars to 
high speed and freedom from accident for rapidly moving carriers. 
Lack of positive and reliable control leads always to destructive 
results, and therefore the railroads have been untiring in their 
efforts to stimulate the perfection of the air-brake as one of their 
most important appliances. Many roads at once adopted the 
device although it was still far from perfect. Three years later, 
the inventor added the triple valve, a distinct advance in reliability 
and facility of operation, and all of the systems which have sur- 
vived are based on a variation of this method of action. Within 
the comparatively short period of twenty-five years, the applica- 
tion of the air-brake even to freight cars has become well-nigh 
universal, resulting in a much more expeditious handling of freight 
and in a greater safety to life and property. 

<l The present work is designed to emphasize the practical ele- 
ments of design and construction, giving particularly the details 
of the Westinghouse and New York systems as applied to railroad 
equipment; a short presentation is also given of the air-brake as 
applied to electric cars. As the material was written especially for 
the correspondence courses of the American School, it should 
appeal both to the trained man who desires accurate information, 
and to those readers who are only interested in keeping up with 
the world's progress along technical lines. 








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5 



THE AIR-BRAKE 



INTRODUCTION 

The development of the many accessory appliances with which 
the rolling stock of our railways is fitted, has been the subject of a 
great deal of study and investigation. Of the many appliances which 
have received careful and systematic study, the braking apparatus 
may be mentioned as one of the most important. 

The time when the question of braking first received attention 
dates back further than the time when highways became sufficiently 
well made and well maintained to permit of vehicles being drawn at a 
moderate rate of speed. When wheeled vehicles, drawn at speeds of 
10 or 15 miles per hour, first made their appearance, it was found 
necessary to provide means by which they could be easily and quickly 
stopped in case of an emergency. The first carts and wagons, built 
for agricultural purposes, were of such construction that the resist- 
ance of the earth and axle were sufficient to bring them to rest in a 
reasonable length of time on ordinary roads. In cases of steep grades, 
the motion was retarded by one or both wheels being locked with 
chains, or by a stone or piece of timber being chained to the axle and 
dragged along the ground behind the vehicle. 

It is interesting to note that the question of braking has steadily 
increased in importance as the demand for higher speed has increased. 
This applies equally well to all classes of vehicles, including railway 
trains, street and interurban cars, automobiles, and wagons. The 
first forms of braking apparatus adopted have formed the basis of 
almost all brake appliances which have since been employed for the 
same class of vehicles. 

Early Forms of Brake. Perhaps one of the first forms of brake 
used was that found on the early stage-coach. It consisted of an iron 
shoe which was chained to the fore part of the coach, and was used 
only on steep grades. To apply this brake, the shoe was removed 
from its hook under the carriage and placed on the ground in front 



2 THE AIR-BRAKE 

of the rear wheel, in such a position that the wheel would roll on it. 
As the wheel rolled on the shoe, the chain became taut, with the result 
that both the shoe and wheel slid over the surface of the ground. 

A railroad is known to have existed as early as 1630, although it 
would hardly be called by that name to-day. .The construction of 
the track as well as that of the cars, was almost entirely of wood. 
Even with this crude construction, it was found necessary to provide 
a brake to control the speed of the cars on the slight grades. The 
form of brake devised to meet the conditions consisted of a wooden 
lever pinned to the frame of the car at one end, in such a manner as 
to permit of its being pressed against the tread of the wheel by hand. 
When not in use, the lever was held off the wheel by means of a 
chain. The principle employed here in resisting the motion of the 
car, is the same as that employed to-day on all railroads — namely, of 
applying the braking or resisting force to the periphery of the wheel. 

As railroads increased in number and their construction improved, 
braking apparatus became more and more a necessity. As a result, 
inventors brought out a number of simple braking appliances. The 
question of braking, however, did not become a very important or 
serious one until the advent of the steam locomotive. Previous to its 
coming, the cars were small and were drawn by animals, and the 
speeds were low; but with the steam locomotive in existence, an 
efficient brake became an absolute necessity. 

This problem received the close attention of inventors and investi- 
gators; and at the close of 1870, the automatic, electromagnetic, steam, 
vacuum, and air brakes were found in use on the railroads in the 
United States. These types of brakes differed chiefly in the manner 
in which the braking power was obtained. Other devices were 
invented, but could not stand the test of actual practice and did not 
come into prominence. 

It might be interesting to note briefly one or two rather 
unique types of brakes not included in any class yet mentioned. The 
Cramer Brake, brought out in 1853, might be mentioned as one of 
these. Its principal feature consisted of a spiral spring which was 
connected to the brake-staff at the end of each car. This spring was 
wound up by the brakeman before leaving the station. The brake 
apparatus on each car was under the control of the engineer, through 
the medium of a cord. This cord was connected to the mechan- 



THE AIR-BRAKE 3 

ism of each brake, and passed through the cars, terminating 
in the cab on the engine. The engineer, desiring to stop his train, 
would shut of! the steam and give the cord a pull, which action resulted 
in releasing the coil springs on the various cars, and applied the 
brakes by winding up the brake-chains. 

The Loughridge Chain Brake is another unique brake, which 
was introduced in 1855. The Loughridge brake consisted of a com- 
bination of rods and chains which extended from a winding drum 
under the engine, throughout the entire length of the train. This 
continuous chain joined other chains under each car, which in turn were 
connected to the brake-levers. The winding drum located under 
the engine was connected by a worm gear to a small friction wheel. 
In operating the brake, a lever in the cab was thrown, which brought 
the small friction wheel in contact with the periphery of one of the 
driving wheels, thereby causing the drum to rotate and wind up the 
chain. The movement of the chain, which was experienced through- 
out the entire length of the train, served to actuate levers and rods 
under each car, which in turn applied the brake-shoes to the treads 
of the wheels. 

The early types of hand-brakes underwent many improvements 
as years went on and as experience demanded. Although during 
many years of early railroading, the braking on all trains was done 
by hand, nevertheless there was a constant desire and demand for 
a practical automatic brake. The rather crude and inefficient types 
of brakes already referred to were obtained only after a great many 
failures. Since about 1870, all forms of brakes have differed chiefly 
in but one respect — namely, in the appliances which are used in 
operating the foundation brake-gear. The foundation brake-gear 
is made up of the rods, levers, pins, and beams, located under the 
frame of the car, the operation of which causes the brake-shoes to be 
pressed against the periphery or tread of the wheel. The present 
scheme of applying the brake-shoe to the periphery of the car wheel 
— which was in use long before the first locomotive made its appear- 
ance — later experience has proven to be the most practical. 

Many forms of brakes were devised prior to the year 1840; but, 
at that time, few locomotives were equipped with braking apparatus. 
About this period, however, when the locomotive tender began to 
take on some definite form, we find the tender fitted with braking 



4 THE AIR-BRAKE 

appliances. Previously, when brakes were provided, they were 
usually found fitted to the cars only. It is only within the last thirty- 
five years that locomotives have been built with brakes fitted to the 
drivers. To-day it is not uncommon to find all wheels on both the 
locomotive and the tender equipped with braking apparatus. 

In 1869, the first Westinghouse air-brake made its appearance. 
This brake is now referred to as the Straight Air-Brake. It was not 
an automatic brake. It consisted chiefly of a steam-driven air- 
compressor and storage reservoir located on the engine; a pipe line 
extending from this reservoir throughout the length of the train; 
a brake-cylinder on each car; and a valve located in the cab 
for controlling the brake mechanism. The train line was connected 
between cars by means of flexible rubber hose with suitable couplings. 
Each car was fitted with a simple cast-iron brake-cylinder and piston, 
located underneath the frame, the piston-rod of which connected 
with the brake-rigging in such a manner that when air was admitted 
into the cylinder, the piston was pushed outward and the brake 
thereby applied. In operating the brake, air was admitted into the 
train line from the storage reservoir by means of a three-way cock 
located in the cab. The air was conducted to the brake-cylinder 
under the various cars by means of the train-pipe. The release of the 
brakes was accomplished by discharging the air in the various brake- 
cylinders and the train-pipe, into the atmosphere, through the three- 
way cock in the cab. This was the simplest and most efficient brake 
invented up to the time of its appearance, and was adopted by many 
railroad companies in this country. 

The Straight Air-Brake system, however, possessed three very 
objectionable features: First, in case of a break-in-two, or of a hose 
bursting, the brake at once became inoperative; second, it was very 
slow to respond in applying and releasing the brakes; and, third, the 
brakes on cars nearest the engine were applied first, causing jamming 
and surging of the cars, which sometimes proved destructive to the 
equipment. In order to overcome these undesirable qualities, Mr. 
George Westinghouse invented the Westinghouse Automatic Air- 
Brake in 1872. This form of brake, which has since gone out of 
service on steam railroads, was known as the Plain Automatic Air- 
Brake. This brake retained the principal features of the Straight 
Air-Brake; but, in addition, each car was provided with an air- 



THE AIR-BRAKE 5 

Teservoir, which supplied air for operating its particular brake- 
cylinder. The charging with air of this auxiliary reservoir, the ad- 
mitting of this air into the brake-cylinder, and the discharge of the air 
from the brake-cylinder to the atmosphere, were accomplished by an 
ingenious device known as the triple valve. A detailed description of 
this valve will be given later. 

In this same year (1872), the Vacuum Brake was invented; but, 
on account of its many undesirable features, it never gained very great 
prominence in this country. This brake was spoken of as the Plain 
Vacuum Brake, and was followed later by the Automatic Vacuum 
Brake. The principal parts of the air-brake were, in general, em- 
bodied in the Vacuum brake. One marked difference existed, 
however, in that, instead of an air-compressor, an ejector was installed 
on the locomotive, which exhausted the air from the train-pipe when 
the system was in operation. 

At the close of the year 1885, there could be found in use on the 
railroads of the United States a number of different types of brakes. 
These could be grouped into two general classes — Continuous or Air 
brakes, and Independent or Buffer brakes. In the Buffer brake, the 
brake-shoes were actuated by rods and levers, which in turn received 
their motion from the movement of the draw-bar. It is easily seen 
that, with such a variety of different forms of braking apparatus, it 
would be impossible to control a train properly if it were made up 
of cars from different railroads having different brake systems. 

Interchangeable Brake System. The one agency which has had 
an important part in placing the braking appliances of our railroads on 
the present high standard of perfection, is the Master Car-Builders' 
Association. This Association, realizing the increasing demand for 
the interchange of cars, saw the need of interchangeable brake 
systems. It was principally through the research of their committees 
that the brake systems of to-day are interchangeable and efficient. 

The first experiment conducted by the committee in 1886 clearly 
showed that any further attempt to use the Independent or Buffer 
brake was not desirable, on account of the severe shocks resulting 
when stopping the train. The effect of the report of the committee 
was the withdrawal of this type of brake from the attention of the 
railroad officials. This left almost the entire field open to the Con- 
tinuous or Air brake system. The committee continued its work 



6 THE AIR-BRAKE 

the following year, and, from the results of a large number of tests, 
reported that the best type of brake for long freight trains was one 
operated by air, in which the valves were actuated by electricity. 
This type of brake stopped the train in the shortest possible distance, 
reduced all attending shocks to a minimum, was released instan- 
taneously, and could be applied gradually. Although the results of 
tests pointed to the superiority of the air-brake in which the valves 
were operated by electricity, yet to-day we find no such systems in 
general use. 

From the time of these tests, the different brake companies 
turned their attention to the style of brake represented by the West- 
inghouse Automatic Air-Brake system. In this system, the most 
important parts are the triple valve, located on the brake-cylinder of 
each car, and the controlling or engineer's brake-valve located in the 
cab. By the year 1893, a number of triple valves and engineer's 
brake-valves had been placed on the market, and representative ones 
were exhibited at the Columbian Exposition in Chicago in that year. 

The committee of the Master Car-Builders' Association, being 
conscious of the fact that the actions of the valves made by the different 
companies were so widely different, proposed a series of tests of triple 
valves, and asked the different companies to submit valves for the 
said tests. The object of the proposed tests was to obtain data from 
which could be formulated a code of tests for triple valves which 
would be satisfactory to all parties concerned. The ultimate aim 
of the committee was to secure triple valves which would operate 
with the same ultimate effect when subjected to identical conditions, 
and which would operate successfully when intermingled with each 
other in a train. 

Such tests were conducted on a specially constructed air-brake 
testing track in the year 1894. Five companies responded with valves 
for the series of tests, of which the valves representing the Westing- 
house and New York companies gave the best results. From the 
results obtained, the committee prepared a code of tests for triple 
valves, which code was soon after adopted by the Association as 
standard. As a result of this action, makers of air-brake apparatus 
endeavored to produce triple valves which would give results as speci- 
fied in the code. This naturally led to interchangeable air-brake 
systems — one of the objects the committee hoped to attain. Many 



THE AIR-BRAKE 7 

triple-valve tests have since been made, and the code has been changed 
from time to time to meet new conditions which have developed. 

To-day there are mainly two air-brake systems in general use 
on steam railroads in this country, namely — the Westinghouse system 
and the New York system. 

WESTINGHOUSE AIR-BRAKE SYSTEM 

The principle on which the Westinghouse Air-Brake system 
operates, is, that if, after the system is charged with compressed air, 
a reduction is made in the brake-pipe pressure, the brake will be 
applied; and in order to release the brake, the brake-pipe pressure 
must be restored. It follows that if any accident occurs to the braking 
apparatus which reduces the pressure in the brake-pipe — such as the 
train parting or hose bursting — the brakes will at once be applied. 
In this respect, the Westinghouse Air-Brake system is automatic. 
The system is composed of the following principal parts: 

1. The steam-driven air-pump located on the engine, which furnishes 
compressed air for the whole system. 

2. The main reservoir, which is located some place about the engine or 
tender, and in which compressed air is stored at a pressure of 90 pounds. 

3. The engineer's brake-valve, which is located in the cab, by means of 
which the flow of air from the main reservoir to the brake-pipe and from the 
brake-pipe to the atmosphere is regulated. 

4. The air-pressure gauge, which is located in plain view of the engineer, 
and which contains two pointers, one red and one "black. The black hand 
indicates the brake-pipe pressure; and the red hand, the main reservoir pressure. 

5. The pump-governor, which regulates the flow of steam to the pump, 
shutting off the steam when the maximum pressure carried in the main reser- 
voir is reached. 

6. The brake-pipe which consists of a pipe under each car with flexible 
hose connection between cars, connecting all the triple valves with the engineer's 
brake-valve. This pipe has been, and is sometimes still, referred to as the train 
line; but as there are other train lines, such as the signal and steam lines, it has 
of late been referred to as the brake-pipe. 

7. The auxiliary reservoir on each car, in which air is stored for use in 
applying the brake. 

8. The brake-cylinder on each car, which contains a piston and rod. 
When air is admitted behind the piston, it causes it to move outward, and, by 
means of suitable connection to the foundation gear, applies the brake. 

9. The triple valve, located under each car, the operation of which admits 
air from the brake-cylinder to the atmosphere, and recharges the auxiliary 
reservoir. 

10. The pressure-retaining valve, which, when closed, will retain a pres- 
sure of 15 pounds in the brake-cylinder and thus prevent a complete release. 






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COCK 





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THE AIR-BRAKE 11 

The general arrangement of the Westinghouse air-brake system 
is shown in Fig. 1, (a, b, and c). This diagrammatically illustrates the 
arrangement and gives the names of the parts as found upon the loco- 
motive, tender, and first car of a passenger train. 

Operation of the Westinghouse Air=Brake. When the brakes 
are in operating condition, the pump-governor is set to maintain a 
pressure of 90 pounds in the main reservoir. This pressure is reduced 
by a valve attached to the engineer's brake-valve, which keeps the 
brake-pipe pressure at 70 pounds, when the engineer's brake-valve 
is in running position. The operation of the brake is controlled by 
the engineer's brake-valve, which has five fixed positions for its 
handle. These positions named in order, beginning from the left, 
are: Release, running, lap, service, and emergency. 

When the engineer's brake-valve is in running position, a pressure 
of 70 pounds is maintained in the brake-pipe by means of the feed- 
valve. The brakes will release when the valve is in this position, but 
they will do so very slowly. 

To make a service application of the brakes, the handle of the 
engineer's valve is placed in service position. In this position, the 
connection between the main reservoir and the brake-pipe, through 
the feed-valve, is closed. Air from the brake-pipe is allowed to escape 
to the atmosphere through ports in the valve. The brake-valve is left 
in this position only for a short time, when it is placed in lap position. 

In the lap position, all working parts are closed and the brakes 
are held applied. 

WTien it is desired to release the brake after either a service or an 
emergency application, the handle of the engineer's valve is placed in 
release position. In this position, direct connection is made between 
the main reservoir and the brake-pipe. 

When it is necessary to make an emergency application, the handle 
of the engineer's brake-valve is placed in emergency position, and 
direct connection is made between the brake-pipe and the atmos- 
phere. This causes a sudden reduction of pressure in the brake-pipe, 
and gives a higher pressure in the brake-cylinder than is obtained 
in service applications. 

Westinghouse Nine and One-Half Inch Air-Pump. The nine and 
one-half-inch pump is shown in Figs. 2, 3, and 4. The pump con- 
sists of two cylinders. The lower (1) is the air-cylinder, and the 



12 



THE AIR-BRAKE 



upper (2) is the steam cylinder. The pistons of these cylinders are 
connected by the hollow rod (3). The air end is very simple, free air 
being drawn in at the valves (4), and discharged under pressure at 
the valves (5). The steam end is somewhat complicated in structure, 

but very simple in principle. The valve 
gear consists of two pistons (6) and 
(7), of unequal diameters, connected 
by the rod (8). This rod gives motion 
to a common D slide-valve (9) which 
admits steam above and below the main 
piston (10). The motion of the piston 
(6) and (7) is obtained by the slide- 
valve (11), Fig. 2, admitting and ex- 
hausting steam at the right of the piston 
(6). Steam enters the valve chamber 
B through the passage A. With the 
parts in the position shown in Figs. 2 
and 4, steam from the chamber B 
passes down through the open port C 
below the piston (10), causing it to rise. 
The steam above the piston (10) passes 
out through the port D into the chamber 
E in the slide valve (9) through the ex- 
haust port F to the atmosphere. The 
piston (10) continues to rise until the 
plate (12) strikes the upper shoulder on 
the rod (13) which raises the slide-valve 
(11). This allows the steam to pass 
from the chamber B through the port 
H around the slide valve (11) through 
the port G into the chamber J. In this 
position, the same pressure acts on both 
sides of the piston (6). Since the 
chamber J is always in communica- 
tion with the exhaust passages through the port K, the pressure on the 
piston (7) is unbalanced. This causes all parts to move to the left. 
This movement opens the port D, permitting steam to force the piston 
(10) downward. At the same time, the port C is put in connection 




LOT 



Fig. 2. Westinghouse 9^ -Inch Air- 
Pump, End Section. 



THE AIR-BRAKE 



13 



with the exhaust port F through the cavity E in the slide-valve (9). 
The piston (10) continues to fall until the plate (12) strikes the button 
on the lower end of the rod (13), drawing the valve (11) downward to 
the position shown in Fig. 2. This closes the port G, and connects 
the chamber / through the port L, the cavity N, and the port M, with 
the main exhaust F. This releases the pressure on the right of the 
piston (6). The pressure on the piston (6) now being greater than 
on the piston (7) will cause both to move to the right, thus completing 
the cycle. 

Eight and One-Half Inch Cross-Compound. This pump is 
coming into use as a result of the growing demand for more air on 
long freight trains. Its capacity 
is about three and one-half times 



H 




L 



Fig. 3. Main Valve Bushing of Westing- 
house 9^-I.nch Air-Pump. 



is about three and one-halt times pi Jr_ 

that of the 9i-inch pump above f^I-.lr V-"-;^--r 
described. As illustrated in Fig. 5, rf -! J ■! | lfj\ 

this pump is of the duplex type, II' • i«t=?_ 

having two steam and two air cylin- 
ders arranged with the steam cylin- 
ders above and the air cylinders 
below. The high-pressure steam 
cylinder is %\ inches in diameter; 
and the low-pressure, 14J inches in diameter, both having a 12-inch 
stroke. The low-pressure air cylinder is 14^ inches in diameter, and is 
located under the high-pressure steam cylinder. The high-pressure 
air cylinder is under the low-pressure steam cylinder, and is 9 inches 
in diameter. The valve gear is located on the top head of the high- 
pressure steam cylinder, and is very similar to that of the 9J-inch 
pump already described. Figs. 6 and 7 show diagrammatically a 
cross-section through the pump. Fig. 6 is a diagram of the parts dur- 
ing an up-stroke of the high-pressure steam side, and Fig. 7 shows 
the down-stroke of the high-pressure steam side. The high-pressure 
steam piston is shown on the right, and the low-pressure on the left. 
The high-pressure steam piston, with its hollow rod, contains the 
reversing-valve rod, and operates the reversing valve in the same 
manner as that of the 9J-inch pump. This valve operates the main 
valve in the same manner as that described in the case of the 9j-inch 
pump. The main slide-valve controls the steam admission to, and 
the exhaust from, both the high- and low-pressure steam cylinders. 



14 



THE AIR-BRAKE 



It is provided with an exhaust cavity, and in addition has four steam 
ports in its face. The two outer and one of the intermediate ports 
communicate with cored passages extending longitudinally in the 
valve, which serve to make the connection between the high- and low- 



trom Boiler 
i" Pipe. 



Exhaust 




Air discharge 
Pipe 



Fig. 4. Westinghouse 9^-Inch Air-Pump, Longitudinal Section. 

pressure cylinders during the expansion of steam from one to the 
other. The other port controls the admission of steam to the high- 
pressure cylinder. 

The valve seat has five ports. Of these, the two at the right, 



THE AIR-BRAKE 



15 



shown in Figs. 6 and 7, lead to the upper and lower ends of the high- 
pressure steam cylinder. The first and third from the left lead to the 
upper and lower ends of the low-pressure steam cylinder; and the 
second, to the exhaust. By following the arrows in Figs. 6 and 7, 
the flow of air and steam through the pump can easily be traced. 

The principle of compounding employed in this pump enables 
it to compress air much more economically than is possible with the 
simple pump. 

Main Reservoir. The use of the main reservoir is for storing: 
an abundant air-supply to be used in charging and releasing the 
brakes. A large reservoir is of great importance, especially in freight 
service, since it provides air for 
an immediate recharging of the 
auxiliary reservoirs without run- 
ning the pump intermittently at 
high rates of speed. The main 
reservoir should have a capacity 
of not less than 24,000 cubic 
inches on passenger engines, and 
not less than 40,000 cubic inches 
on freight engines. The main 
reservoir is usually located some- 
where on the engine; but some- 
times it is placed on the tender, 
though the latter location necessi- 
tates two extra pipe connections 
between the engine and the tender, 
which is not good practice. A 
good practice is to divide the main 
reservoir, and place half on each 
side under the running-board. 
The air is then delivered to 
one side and taken out of the other, the two reservoirs being connected. 
This system has two decided advantages over others, one being that 
the air is cooled, thus causing the moisture to be collected in the 
reservoir. The other advantage is, that the distance between the 
inflow and out-take prevents much of the dirt and oil from being 




Fig. 5. Westinghouse 8^-Inch Cross- 
Compound Pump. 



16 



THE AIR-BRAKE 



carried into the brake-pipe. The main reservoir should always be 
drained after each run. 

Air-Pump Governor. The purpose of the governor is to cut off 
the steam supply to the pump when the desired main-reservoir pres- 
sure has been reached. Fig. 8 is a section through the governor. 
When the pump is in operation, steam enters the governor at B, passes 
the valve (2), and enters the pump through the pipe C. An air con- 
nection is made at A with the main reservoir. Main-reservoir air thu> 



(• ::•'.-•'::::,'/.■':•:::.'//: v.v,w/0 




^^2^\ 



Fig. 6. Section of 8^-Inch Cross-Compound Pump, Up-Stroke, 
High-Pressure Steam Side. 

enters the chamber D; and as soon as this pressure on diaphragm (1) 
is sufficient to overcome the tension of the spring (3), the diaphragm 
(1) will be raised and will unseat pin valve (4). Air will then flow 
down into the chamber E, forcing the piston (5) downward, thus 
seating the valve (2) and shutting off the steam from the pump. When 
the air-pressure falls below that carried in the main reservoir, the 
spring (3) will force the diaphragm (1) down, and will seat the pin 



THE AIR-BRAKE 



17 



valve (4). The air in the chamber E will now escape to the atmos- 
phere through the small relief port F, and the spring (6) will open 
the valve (2), again admitting steam to the pump. 

While the pin valve is unseated, there is a small escape of air to 
the atmosphere through the port F. This leakage, together with a 
leakage of steam through a small port in the valve (2), serves to keep 
the pump slowly operating and thus avoids trouble from condensation 
in the steam pipe. 






|5team 
Inlet 





Fig. 7. 



Section of 8% -Inch Cross-Compound Pump, Down- 
Stroke, High-Pressure Steam Side. 



Westinghouse Engineer's Brake- Valve. The construction of 
the engineer's brake-valve is illustrated in Figs. 9, 10, and 11. Fig. 
9 is a section through the body, with the rotary valve removed, and 
shows the different positions of the handle. Figs. 10 and 11 are 
vertical sections of the entire valve taken at right angles to each other. 
The description of the operation of the valve is given in the order in 
which it is generally used when braking a train. 



18 



THE AIR-BRAKE 



Running Position. The valve is shown in running position in 
Fig. 10. Main-reservoir air from the chamber A flows through the port 
B in the rotary valve (1) into the passage C, which conducts it to the 
feed-valve. (The course of the air through the feed-valve will be 
described later.) From the feed-valve, the air is conducted by the 




Fig. 8. Section through Air-Pump Governor. 



passages D and E to the chamber F, and from here to the brake-pipe. 
The cavity G in the rotary valve (1) connects the passage E with the 
port H, permitting air at brake-pipe pressure to enter the chamber 
I and flow through the passage J into the equalizing reservoir. 



THE AIR-BRAKE 



19 



Brake-pipe pressure now exists on both sides of the equalizing piston 
(2). Air continues to flow into the brake-pipe and equalizing reser- 
voir until the pressure reaches 70 pounds. At this pressure, the feed- 
valve closes the passage leading from the main reservoir. In this 
position, the brake-pipe is kept charged to 70 pounds' pressure; 
90 pounds' pressure is maintained in the main reservoir; and the entire 
system is ready for an application. 

Service Position. When it is desired to reduce the speed of a 
train or to stop at a station, the handle of the engineer's brake-valve 
is placed in service position until the brake-pipe reduction causes 
enough air to enter the brake-cylinders to produce the desired result. 
When the brake-pipe reduction is sufficient, the handle of the valve 
is placed in lap position as described below. In service position 



m 



Main Reservoir 
Pressure 





Fig. 9. Section through Engineer's Brake-Valve.— Rotary Valve 
Removed, and Different Positions of Handle Shown. 

a groove in the rotary valve (1) connects the port K with the groove 
L, both of which are in the valve-seat. This permits air from the 
chamber I and the equalizing reservoir to discharge through the 
passage M to the atmosphere, thus reducing the pressure on the top 
side of the equalizing piston (2). Brake-pipe pressure, being greater 
than the pressure on the top side of the equalizing piston (2), forces 
it upward, opening the attached discharge valve, and permitting air 
to flow from the brake-pipe through the port N and the passage to 
the atmosphere. When the pressure in the equalizing reservoir is 
reduced the desired amount, the handle of the engineer's brake-valve 






20 



THE AIR-BRAKE 



is moved to lap position. Air continues to discharge through the 
above-mentioned passages until the pressure in the brake-pipe has 
reduced slightly below that in the equalizing reservoir and chamber I; 
then the greater pressure acting on the top of the piston (2) causes it 
automatically to close the discharge valve. When the piston (2) 
closes the discharge valve, the pressure in the brake-pipe and equaliz- 
ing reservoir is about the same. 

The equalizing reservoir is 10 inches in diameter and 12 inches 




Feep 
Valve, 



Fig. 10. Engineer's Brake- Valve in Running Position. 

long. Its purpose is to increase the volume of air so that the pressure 
in the chamber I will not drop too rapidly when the handle is placed 
in service position. If a reduction of pressure be made in the equaliz- 
ing reservoir, and the handle placed in lap position, air will exhaust 
from the brake-pipe until its pressure is the same as that in the 
equalizing reservoir. 

Lap Position. This position is the one in which the valve handle 
is placed after a light reduction has been made in the brake-pipe. 



THE AIR-BRAKE 



21 



It remains in this position, holding the brake applied until a further 
brake-pipe reduction is desired or until the brake is released. In this 
position, all ports are operatively closed. No air can enter the brake- 
pipe from the main reservoir, and no air from the brake-pipe can 
escape to the atmosphere. 

Emergency Position. In case of an emergency, the handle of 
the brake-valve is moved to the extreme right. In this position, 
direct-application-and-exhaust port M is connected with direct-appli- 
cation-and-supply port E by the cavity G in the rotary valve (1). 
This establishes direct communication between the brake-pipe and 
the atmosphere, and a sudden reduction of pressure occurs in the 




RE.5.ERVOIF* 



To Brake Pipe 



Fig. 11. Engineer's Brake- Valve in Release Position. 

brake-pipe. This causes all brakes to apply very quickly with full 
braking pressure. 

Release Position. The parts of the valve are shown in release 
position in Fig. 11. The purpose of this position is to provide large 
ports through which air can flow from the main reservoir to the brake- 
pipe and quickly recharge the system and release the brakes. Air 
from the main reservoir flows from the chamber A, through the port 
P, the cavities Q and G, into the passage E and to the brake-pipe. 
The ports H and K both conduct air to the chamber 7, and the 



22 



THE AIR-BRAKE 



equalizing reservoir is charged through the passage J to the same 
pressure as exists in the brake-pipe. 

The brake-valve handle should not remain in this position too 
long, as there is danger of overcharging the brake-pipe and the auxiliary 
reservoirs. The warning port R in the rotary valve (1) permits a 
small amount of air to escape from the chamber A to the exhaust 

passage M, making a noise 
which notifies the engineer 
that the brake-valve is still 
in release position. 

Slide-Valve Feed-Valve. 
The purpose of the feed- 
valve is to maintain a pre- 
determined pressure in the 
brake-pipe while the engi- 
neer's valve is in running 
position. Figs. 12 and 13 
illustrate the slide-valve 
feed-valve. Fig. 12 is a 
central section through the 
supply-valve case and 
governing device. Fig. 13 
is a transverse section 
through the supply-valve 
<jase, and a central section 
through the regulating valve 
and spring-box. The ports 
A and B register with the 
ports in the brake-valve. 
The port A is in communi- 
cation through the engineer's 
valve with the main reservoir, when the engineer's valve is in running 
position. Air enters the feed-valve at A, and has at all times free com- 
munication with the chamber C. The chamber C is separated from the 
chamber D by the supply piston (1). Connection is made between the 
chamber D and the brake-pipe through the passage E, the regulating 
valve (2), the chamber F, and the port B. The regulating valve (2) is 
normally held open by the tension of the spring (3) upon the diaphragm 




Fig. 



12. Central Section through Supply-Valve 
Case and Governing Device of Slide- 
Valve Feed-Valve. 



THE AIR-BRAKE 



23 



(4). When the valve (2) is open, the chamber D has brake-pipe pressure 
acting upon it as described above. When the handle of the engineer's 
brake-valve is placed in running position, main-reservoir air enters 
the chamber C and forces the piston (1) to the right, as shown in Fig. 
12. This draws the slide valve (5) to the right, uncovers the port G, 
and direct connection is made between the main reservoir and the 
brake-pipe through the chamber C, the port G, and the passage B. 




Fig. 13. Transverse Section through Supply- Valve Case, and 
Central Section through Regulating Valve and Spring- 
Box of Slide-Valve Feed- Valve. 

Air now flowing from the main reservoir will raise the brake-pipe 
pressure until the pressure in the chamber F is sufficient to overcome 
the tension of the regulating spring (3). This requires 70 pounds 
in the ordinary equipment. The spring (6) will now seat the regulat- 
ing valve (2), and cut off communication between the brake-pipe 
and the chamber D. The pressure in the chambers C and D will then 
equalize through leakage past the piston (1), when the spring (7) 
will move the piston (1) and the slide-valve (5) to the left, closing the 



24 



THE AIR-BRAKE 




to &rake Pipe 



Fig. 14. Quick- Action Triple Valve, Release Position. 




To Brake Pipe 



Fig. 15. Quick- Action Triple Valve, Service Application. 



THE AIR-BRAKE 



25 



port G and shutting off communication between the main reservoir 
and the brake-pipe. A subsequent reduction of brake-pipe pressure 
will cause the regulating spring (3) to unseat the valve (2), and the 
accumulated pressure in the chamber D will discharge to the brake- 
pipe. The pressure in the chamber C being greater than that in the 
chamber D, the piston (1) will move to the right and uncover port 
G, allowing the brake-pipe to be recharged. 

Quick- Action Triple Valve. The quick-action triple valve is 
shown in its four positions by Figs. 14, 15, 16, and 17. The principal 
parts are numbered as follows: (1) Slide valve, (2) main piston, 



lUlSa 




Fig. 16. Quick- Action Triple Valve, Lap Position. 

(3) graduating valve, (4) graduating stem, (5) graduating spring, 
(6) emergency piston, (7) emergency valve, and (8) check-valve. 

Charging or Release. Fig. 14 shows the position of the triple 
valve when the auxiliary reservoir is being charged and the brake 
is being released. Air enters the triple valve at the point marked 
"To Brake-Pipe, ,, and follows the passage A through the port B into 
the chamber C, through the feed -groove D, over the slide-valve (1), 
to the auxiliary reservoir. This flow of air will continue until the 
pressure in the auxiliary reservoir is equal to the pressure in the brake- 




26 



THE AIR-BRAKE 



pipe. This pressure is 70 pounds in the ordinary equipment. At 
the same time, air from the brake-cylinder enters the triple valve at 
the point marked "To Brake-Cyl'd," and passes through the port 
E, through the cavity F in the slide-valve (1) (see Fig. 18), and into 
the exhaust port G to the atmosphere. 

Service Position. Fig. 15 shows the position of the triple valve 
during a service application. A reduction of about 5 pounds in the 
brake-pipe reduces the pressure in the chamber C, and causes the 
piston (2) to .move to the left until it strikes the graduating stem (4). 
This closes the feed-groove D and opens the graduating valve (3). 




To Brake Pipe. 



Fig. 17. Quick- Action Triple Valve, Emergency Application. 

Auxiliary-reservoir air now flows into the brake-cylinder through the 
port H, passing the graduating valve (3) into the port I, which 
registers with the port E. 

Lap Position. As soon as the pressure on the auxiliary-reservoir 
side of the piston (2) has fallen below the brake-pipe pressure, the 
piston (2) will move to the right and seat the graduating valve (3). 
This is known as lap position, and is shown in Fig. 16. The flow of 
air from the auxiliary reservoir to the brake-cylinder how ceases. 
Since the difference in pressure on the two sides of the piston (2) is 



THE AIR-BRAKE 



27 



not sufficient to overcome the frictional resistance of the slide-valve 
(1), all ports remain in the position shown until another reduction 
in the brake-pipe is made or until the brake is released. A service 
reduction of 25 pounds in the brake-pipe will equalize the pressure in 
the auxiliary reservoir and brake-cylinder at about 50 pounds, this 
being the maximum pressure obtainable in a service application. 

Emergency Application. A sudden reduction of air in the brake- 
pipe will cause the piston (2) to move to the left with such force that 
its impingement against the graduating stem (4) will compress the 
graduating spring (5), as shown in Fig. 17. In this position of the 
parts, a diagonal slot J in the slide valve (1), Fig. 18, registers with the 
port K, which opens into the chamber L above the emergency piston 
(6). This permits auxiliary-reser- 
voir air to act on the piston (6), 
forcing it down, unseating the 
emergency valve (7), and allowing 
the air-pressure in the cavity M 
to enter the brake-cylinder. Brake- 
pipe pressure then lifts the check- 
valve (8), and air rushes into the 
brake-cylinder. At the same time, 
the auxiliary-reservoir air has a 
direct passage into the brake-cylin- 
der through the port N, which 
registers with the port E. As the opening through the check- valve 
(8) and the emergency valve (7) is comparatively large, the brake-pipe 
discharges into the brake-cylinder very rapidly. This causes a quick 
reduction of pressure in the brake-pipe and affects the next triple in 
the train, causing it to act in the manner just described. Each triple 
valve in its turn is affected by the sudden drop in brake-pipe pressure, 
so that a full emergency application in a 50-car train can be made in 
about three seconds. The release from an emergency application is 
made in the same way as the release from a service application. In 
an emergency application, the pressure in the brake-cylinder rises to 
about 60 pounds, being about 10 pounds higher than that obtained 
in a full service application. 

Plain Triple Valve. Fig. 19 shows a section of the plain triple 
valve. This valve is like the quick-action triple valve, except that 




Fig. 18. Slide- Valve and Seat of Quick- 
Action Triple Valve. 



28 



THE AIR-BRAKE 



the slide-valve (3) and the axis of the main piston (2) are vertical 
instead of horizontal, and the emergency valve mechanism is omitted. 
In a service application, the operation of the plain triple is exactly the 
same as that of the quick-action triple valve, as already described. 













Fig. 19. Section of Plain Triple Valve. 



When a sudden reduction of air is made in the brake-pipe, the piston 
(2) strikes the graduating stem (4), compresses the spring (5), and 
moves to its extreme lower position. The upper edge of the slide- 
valve (1) is now below the lower edge of the port E, and a direct com- 



THE AIR-BRAKE 



29 



munication between the auxiliary reservoir and the brake-cylinder is 
made. This will cause a quick application of the brake; but the 
final pressure in the brake-cylinder is no greater than if a full service 
application were made. 

The plain triple valve is used largely on the tender and locomotive 
equipment, but is gradually being replaced by the quick-action triple. 

Combined Freight-Car Cylinder, Reservoir, and Triple Valve. 
Fig. 20 shows the combined freight-car cylinder and reservoir, which 
is the usual form ^of equipment employed on freight-cars. Referring 
to Fig. 20, (1) is the quick-action triple valve; (2) is the auxiliary 
reservoir , which is simply a hollow cast-iron shell for the purpose of 
storing air for use in the brake-cylinder upon the same car; (3) is a 
release valve usually placed above the auxiliary reservoir for the pur- 
pose of releasing the brake in case of necessity; (4) is a pipe connecting 




Fig. 20. Combined Freight-Car Cylinder, Reservoir, and Triple Valve. 

the triple valve with the brake-cylinder; (5) is the brake-cylinder; 
(6) is the piston ; (7) is the packing leather, which is pressed against 
the cylinder to prevent air from leaking past the piston; (8) is the 
follower plate that holds the leather to the piston; (9) is the spring 
expander, which presses the leather out against the cylinder wall; 
and (10) is a release spring which brings the piston back to the position 
shown after the air is exhausted from the cylinder. A rod extends 
from the valve (3) to either side of the car. If either rod is pulled, 
the pressure in the auxiliary reservoir will be exhausted and thus will 
release the brake. There is a small groove called the leakage groove, 
shown by dotted lines at A. This groove permits any small leaks 
of air which may enter the cylinder, to pass around the piston (6), 
and thus prevents its being moved outward and setting the brake. 

The movement of the piston (6) should be such that the pressure 
in the auxiliary reservoir and brake-cylinder will equalize at 50 pounds 



30 



THE AIR-BRAKE 



in a full service application. To secure this pressure, the stroke of 
the piston must be about 8 inches. If the brake is applied when the 
car is not in motion, the stroke of the piston is called the standing 
travel; when in motion, it is called the running travel. Because of 
the slack in loose fitting parts, shoes pulling down on the wheels, etc., 
the running travel is about 1 \ inches greater than the standing travel. 
For this reason, the brake rigging must be adjusted to give a piston 




Fig. 21. Section of Pressure-Retaining Valve. 

travel of about 6J inches when the car is not in motion. The brake- 
cylinder commonly used in freight-car equipment is 8 inches in 
diameter. When a larger cylinder is used, the auxiliary reservoir 
must be increased proportionally. 

Pressure=Retaining Valve. Fig. 21 shows a section through this 
valve. A pipe is connected at A which comes from the exhaust port 
of the triple valve. When the valve handle (1) is down, the exhaust 



THE AIR-BRAKE 



31 






Exhaust 



from the triple valve enters at A, passes the valve (2), and out at the 
port B. If the handle (1) is turned horizontally, as shown in Fig. 21, 
the air from the triple valve flows around the valve (2), lifting the 
weighted valve (3) , and passes to the atmosphere through the port C. A 
pressure of over 15 pounds 
will raise the weighted valve 
(3). When the brake-cylin- 
der pressure has become 
reduced to 15 pounds, the 
weighted- valve (3) seats, and 
the remaining 15 pounds 
pressure is retained in the 
brake-cylinder until the han- 
dle (1) is turned down. 
Pressure-retaining valves are 
used mostly on freight-cars; 
but some roads that have 
long, heavy grades use them 
on passenger cars also. 
These valves should be so 
located that they can be 
reached while the train is in 
motion. The usual location 
on freight-cars is at the end 
of the car, just under the 
foot-board. 

High-Speed Brake. It 
has been known for several 
years that as the speed of 
the train is increased, the 
maximum brake-shoe pres- 
sure may also be increased 
without danger of skidding 
the wheels. That is, a 
train going at a speed of 80 miles an hour would require a much 
greater brake-shoe pressure to skid the wheels than a train going 5 
miles an hour. This fact has been taken advantage of in the design 
of the high-speed brake. Instead of carrying a brake-pipe pressure 




Fig. 22. Section of Automatic Reducing Valve. 



32 THE AIR-BRAKE 

of 70 pounds when the high-speed brake is in operation, 110 pounds 
is carried. When a full service application is made, 85 pounds pres- 
sure is obtained in the brake-cylinder. If this pressure were allowed 
to continue in the brake-cylinder until the train stopped, there would 
be danger of skidding the wheels. In order to prevent this, a valve 
known as the automatic reducing valve is used. This valve is shown 
in Figs. 22 and 23. The chamber A above the piston (1), Fig. 22, 
has at all times communication with the brake-cylinder by means of 
a pipe connection. When the pressure in the brake-cylinder is 60 
pounds or less, the parts of the valve are in the position shown. If, 
during a heavy service application, the pressure in the brake-cylinder 
becomes greater than 60 pounds, its action on piston (1) will be suf- 
ficient to overcome the tension in the spring (2); and piston (1), 
together with the slide-valve (3), will move downward until the port C 
registers with the triangular port B, which is always in communication 
with the chamber A. Air from the brake-cylinder now escapes 
through chamber A and ports B and C to the atmosphere. This 
exhaust of air will continue until the brake-cylinder pressure is reduced 
to 60 pounds. The spring (2) then raises the piston (1), causing 
the slide-valve (3) to close the exhaust port C. In the operation 
just described, the greatest width of the triangular port B is exposed 
to the port C. These ports are so proportioned that in this particular 
position, the surplus air is discharged from the brake-cylinder as 
rapidly as it is admitted through the service application port of the 
triple valve. 

In an emergency application, the violent admission of air into the 
brake-cylinder so suddenly increases the pressure that the piston (1) 
is forced to the lower end of its stroke. In this position, only the 
apex of the triangular port B in the slide-valve (3) registers with the 
port C, and a comparatively slow discharge of brake-cylinder air- 
pressure takes place while the train is at its highest speed; but the 
area of the opening of the port B gradually increases as the pressure 
decreases, until the pressure in the brake-cylinder is 60 pounds, after 
which time the port C is closed as in a service application. 

The high-speed equipment is used principally on fast passenger 
trains. Fig. 23 shows the general arrangement under a passenger 
car of the auxiliary reservoir, brake-cylinder, triple valve, high-speed 
reducing valve, and pipe connections. The arrangement of the brake- 



THE AIR-BRAKE 



33 



cylinder and the auxiliary reservoir is different from that used on 
freight-cars, in that they are separate, and the triple valve is bolted 
to the brake-cylinder instead of to the auxiliary reservoir. On a 
locomotive used in handling both the high-speed and standard equip- 
ments, the engineer's brake-valve is fitted with two feed-valves; and 
the air-pump, with a duplex governor. One feed-valve is adjusted 
for 70 pounds, and the other for 110 pounds. One pump-governor 
is adjusted to maintain a pressure of 90 pounds in the main reservoir, 
and the other a pressure of 130 pounds. 

The equipment on the locomotive may be changed from the 
standard to the high-speed by closing a cut-out cock in the pipe leading 




Automatic 

Reducing valve 

Triple valve 



Auxiliary Rcservohr 



Fig. 23. Automatic Reducing Valve Applied to Car. 



to the 90-pound pump-governor, and changing the feed-valve handle 
so that the 110-pound feed-valve is operative instead of the 70-pound 
feed-valve. 



WESTINGHOUSE "E T" LOCOMOTIVE BRAKE 

EQUIPMENT 

In a paper read before the 1906 meeting of the Air-Brake Asso- 
ciation, Mr. F. H. Parke stated that the possible braking power of a 
single modern locomotive was over 10 per cent of a 50-car freight 
train, 12 per cent of a 12-car Pullman train, 25 per cent of a 10-car 
passenger train, and 35 per cent of a 6-car passenger train. These 
figures show that the brake equipment of the locomotive should 
receive special attention, and that the brake equipment commonly 
used on locomotives should be improved. 



34 THE AIR-BRAKE 

The first step taken in this direction was the development of the 
combined automatic and straight-air equipment for locomotives. 
This system provided a means for applying and releasing the brakes 
on the cars in the train. It greatly increased the control of the engine 
in switching and in handling the slack in long freight trains, but it 
had many undesirable features. It was greatly simplified and im- 
proved by the invention of the so-called "E T" locomotive brake 
equipment. 

The "E T" equipment possesses all the advantages of the com- 
bined automatic and straight-air equipment, and several additional 
ones which are necessary to give satisfactory results in braking long 
trains. It can be applied to any locomotive without change or modifi- 
cation of any of its parts, and the locomotive so equipped can be used 
for any class of service. The Westinghouse Company makes the 
following claims for the "E T" equipment: 

1. "The locomotive brakes may be controlled with or independently of 
the train brakes, and this without regard to the position of the locomotive in 
the train, whether coupled to another, as in double heading, or used as a helper 
and assigned to any position in the train. 

2. "They may be applied with any desired pressure between the mini- 
mum and the maximum attainable; and this pressure will be automatically 
maintained in the locomotive brake-cylinders, regardless of leakage and 
variation in piston travel — undesirable though these defects are — until released 
by the brake- valve. 

3. "They will remain applied when the engineer places the automatic 
brake- valve handle in full release, then in lap position preparatory to making 
the second application in a two-application stop, thus making a more uniform 
stop and requiring a lighter second application. 

4. "They can be perfectly graduated on or off, either in the automatic 
or in the independent application; hence, in all kinds of service, the train may 
be handled without shock or danger of parting; and in passenger service espe- 
cially, smooth and accurate stops can be made with greater ease than was here- 
tofore possible." 

Fig. 24 gives the names of all parts used in the equipment, and 
shows the scheme and sizes of piping. The parts not to be found in 
the quick-action automatic equipment as commonly installed on the 
locomotive, are as follows: 

1. A duplex pump-governor. 

2. A distributing valve, and small double-chamber reservoir to which it 
is attached. This valve performs the functions of triple valve, auxiliary reser- 
voir, double check-valve, and high-speed reducing valve on the locomotive. 



36 THE AIR-BRAKE 

3. Two brake-valves, one of which is automatic and operates both the 
train and locomotive brakes; the other an independent valve operating the loco- 
motive brakes only. 

4. A feed-valve, located in the reservoir pipe to regulate the brake-pipe 
pressure. 

5. A reducing valve, which reduces the main-reservoir pressure for the 
independent brake- valve and for the air-signal system when used. 

6. A single-pointer gauge to indicate the locomotive brake-cylinder 
pressure. 

Manipulation. The instructions for operating the "ET" 
equipment are very similar to those given for the combined automatic 
and straight-air equipment. The automatic brake-valve has six 
fixed positions for its handle, while the independent brake-valve has 
but five. The positions for the automatic brake-valve are: Release, 
running, holding (driver brake), lap, service, and emergency; and 
those for the independent brake-valve are : Release, running, lap, slow 
application, and quick application. 

The handles of both brake-valves should be kept in running 
position when not in use. 

To make a service application on both locomotive and train 
brakes, move the handle of the automatic brake-valve to service 
position long enough to secure the required brake-pipe reduction; 
then move the handle back to lap position. All brakes will remain 
applied as long as the valve remains in this position. 

The train brakes may be released by moving the handle of the 
automatic brake-valve to release position. When the valve is in 
release position, care should be exercised that the brake-pipe does not 
become overcharged. This action does not release the locomotive 
brakes. If the handle is moved from release to holding position, the 
locomotive brakes will still remain applied. They may be graduated 
off by short successive movements of the handle between running and 
holding positions, or by placing the handle at once in the running 
position. If a full stop is not desired, the handle of the automatic 
brake-valve should be placed in service position until the required 
reduction in brake-pipe pressure is obtained; then moved to lap 
position. After the speed has dropped' sufficiently, place the handle 
in release position until all the train brakes are released and the slack 
has had an opportunity to adjust itself; then place the handle in 
running position to release the locomotive brakes. 

An emergency application is made with the automatic brake- 



THE AIR-BKAKE 37 

valve in exactly the same manner as with the engineer's brake-valve 
commonly installed on locomotives. 

If only the independent brake-valve is being used, the handle of 
the automatic brake-valve should be carried in running position. 
The locomotive brakes may be released by placing the handle of the 
independent brake-valve in running position. When the handle of 
the automatic brake-valve is not in running position, the only way 
in which the locomotive brakes can be released is by placing the handle 
of the independent brake-valve in release position. The locomotive 
brakes may be released under any and all conditions by placing the 
handle of the independent brake-valve in release position. The 
independent brake-valve should be used very carefully when handling 
long trains or in switching service, as damage to draft gears might 
result if the slack in the train is permitted to run out hard. If an 
emergency case arises, the automatic brake should be applied instantly, 
even though the independent brake is being used. The safety-valve 
on the distributing valve will prevent any excessive brake-cylinder 
pressure on the locomotive. 

In handling trains on long grades, the application of the train 
brakes and locomotive brakes should be alternated to prevent any 
overheating of the wheels. When leaving the locomotive while doing 
work about or near it, the independent brake-valve should always be 
left in application position. 

When double-heading, the double cut-out cock in the brake-pipe 
below the automatic brake-valve should be closed, and the valve 
should be left in lap position, except on the locomotive from which 
the brakes are being operated. 

In order to simplify the description of the various parts of the 
equipment, the following names of pipes are given (see Fig. 24) : 

Reservoir Pipe. The pipe connecting the main reservoir to the auto- 
matic brake-valve, distributing valve, feed-valve, and reducing valve. 

Feed-Valve Pipe. The pipe connecting the feed- valve to the automatic 
brake- valve. 

Reducing-V alve Pipe. The pipe connecting the reducing valve to the 
independent brake-valve and the air-signal system. 

Brake-Pipe. The pipe connecting the automatic brake- valve to the 
distributing valve and the triple valves on the cars in the train. 

Brake-Cylinder Pipe. The pipe connecting the distributing valve to the 
brake-cylinders on the engine and tender. 



38 



THE AIR-BRAKE 



Application-Chamber Pipe. The pipe connecting the application cham- 
ber of the distributing valve to the automatic brake-valve, through the inde- 
pendent brake- valve. 

Double- Heading Pipe. The pipe connecting the application chamber of 
the distributing valve to the automatic brake- valve, through the double cut-out 
cock. 



The main-reservoir cut-out cock is used to cut off the supply of air 
when removing any part of the equipment for cleaning or repairing, 
except the governor. Before it is closed, however, the double cut-out 
cock below the automatic brake-valve should be turned to close the 
brake-pipe, and the handle of the automatic brake-valve should be 
placed in release position. This is done so as to prevent lifting from 
its seat the rotary valve of the automatic brake-valve or the slide- 
valve of the feed-valve. The automatic brake-valve receives air from 
the main reservoir direct and through the feed-valve. The check- 
valve in the signal pipe prevents air from flowing back from the signal 

pipe when the in- 
dependent brake- 
valve is being used. 
The pump-govern- 
or has three pipe 
connections — one 
from the reservoir 
pipe to the maxi- 
mum pressure head ; 
one from the feed- 
valve pipe to the 
upper connection of 
the excess pressure 
head ; and one from 
the automatic 
brake-valve to the 
lower connection of 
the excess pressure 
head. 

Distributing Valve. The distributing valve, shown in Figs. 25 
and 26, has five pipe connections. On the reservoir are cast the 
following letters indicating these connections: MR— main reservoir 




Fig. 25. 



Distributing Valve and Double-Chamber Reservoir 
of "ET" Equipment. 



THE AIR-BRAKE 



39 



pipe; DH — double-heading pipe; AC — application-chamber pipe; 
BC — brake-cylinder pipe; and BP — brake-pipe. 

Fig. 27 is a section through the distributing valve. The prin- 







Fig. 26. Part Sectional View of Distributing Valve and Double-Chamber Reservoir 

of "ET" Equipment. 

ciples governing the operation of this valve are the same as those 
previously described in the standard equipment commonly used. 
The chief difference is the manner in which air-pressure is supplied 




To Application 

Chamber 



Pressure 
Chamber 



Safety Valve- ^ 
Fig. 27. Section through Distributing Valve of "ET" Equipment. 

to the brake-cylinders of the locomotive. It consists chiefly of a plain 
triple valve, an auxiliary reservoir, and a small brake-cylinder, the 



40 



THE AIR-BRAKE 



piston-rod of which operates two slide-valves instead of being con- 
nected to the brake-rigging. The piston travel is always constant. One 
of the slide-valves mentioned admits air to the brake-cylinders of 
the locomotive, and the other releases or exhausts this air. The 
triple valve and auxiliary reservoir are used in automatic applications 
only, and are called, respectively, the equalizing portion and the 




Plan of Graduating Valve.. 




Face of 51 ide Valve. 





K "V— .. ' ) "iR 

1 .....»^to. 









Plan of Slide Valve. 




j-eD 



«T 



J ^0 Q-p 




Plan of Slide Valve 5eah 



Fig. 28. Graduating Valve, Equalizing Slide-Valve, and Slide- 
Valve Seat of Distributing Valve of "ET" Equipment. 

pressure chamber. The slide-valve connected to the piston-rod of the 
small brake-cylinder, which admits air to the brake-cylinders of the 
locomotive, is called the application valve, while that one which 
e> hausts this air is called the exhaust valve. It is easily seen that the 
entire operation of the locomotive brakes consists in admitting or 



THE AIR-BRAKE 



41 



releasing air-pressure into or out of the application chamber. In 
independent applications, this is done directly by operating the inde- 
pendent brake-valve; while in automatic applications, it is accom- 
plished by means of the equalizing piston and the air-pressure stored 
in the pressure chamber. 

Fig. 28 is given to show the correct location of ports in the equaliz- 
ing "sjalve and slide-valve. 

Since the ports in the valve cannot be clearly indicated in Fig. 
27, diagrammatic illustrations shown in Figs. 29, 30, 31, 32, 33, 34, 



0ZZZZZZZZZZZZZZZZZZZ& 



^S^ Brake - 
^ — 



Main 
Reservoir 1 



Double- _ 
Heading |t 




Application ^ ^ 
Chamber SSLE^ 



Application 



Brake - 
Pipe 



Safety 
Valve 



^VVV^W ^'AV^^^T^ 



,w\v\w>ws 



Fig. 29. Distributing Valve, Charging or Release Position, Automatic or 

Independent. 

35, and 36 will be referred to in explaining the operation of the valve. 
These diagrams show the parts distorted and not as actually con- 
structed. 

The operation of the valve when automatic applications are made, 
is as follows : 

Charging. Fig. 29 shows the movable parts of the valve in 
charging position. In this position, the chamber A is in connection 
with the brake-pipe ; and air is free to pass around the top of the piston 



42 



THE AIR-BRAKE 



(1) through the feed-groove B and the port C, to the pressure chamber, 
until the pressure on both sides of the piston becomes equal. 

Release. The position shown in Fig. 29 is also the release 
position, and is the position the parts take when the automatic brake- 
valve handle is placed in release position. In this position, the pres- 
sure in the chamber A is greater than that in the application chamber; 
consequently the equalizing piston (1) is moved to the position shown. 
This movement of the piston moves the graduating valve (2) and the 
slide-valve (3) to the release position shown, but does not release the 



M////////////7 77777? 



~1 WM^ Brake- 
^ Cglinder 




Application ^ 
Chamber^ 

1 






Brake- 
Pipe 

Safety 
Valve 



Fig. 30. Distributing Valve, Automatic Service Position. 

locomotive brakes. To accomplish this, either the automatic brake- 
valve must be placed in running position or the independent brake- 
valve must be moved to release position. In either case, the applica- 
tion-chamber pipe is opened to the atmosphere, and the air in the 
application chamber is exhausted. The air in the chamber E will also 
be exhausted, since it is connected to the application chamber by the 
port D. This permits the brake-cylinder pressure in the chamber 
F to move the piston (4) to the left until the exhaust ports G and H 



THE AIR-BRAKE 



43 




permit the brake-cylinder pressure to escape. The double-heading 
pipe must always be kept closed at the double cut-out cock below the 
automatic brake-valve, unless there are two engines at the head of 
the train. In this case, the engine from which the brakes are con- 
trolled should have its double-heading pipe closed, while on the other 
engine it should be open. 

Service. When a service application is made with the automatic 
brake-valve, the brake-pipe pressure in the chamber A is reduced; 
and piston (1), together with the graduating valve (2) and the slide- 




Brake - 
3-^ Cylinder 



Application 
Chamber is 



-r 



Chamber. ^' 

Sis 



vq Pressure 



s 



^VV^V^VvVA^^^^^^^ 






p 



Brake- 
Pipe* 

Safety 
Valve 



^^ 




Fig. 31. Distributing Valve.— Service Lap Position. 

valve (3), is moved toward the right to the position shown in Fig. 30. 
In this position, the port I in the slide-valve registers with the port J 
in the seat, and permits air from the pressure chamber to flow into the 
application chamber and the chamber E through the port D. This 
pressure forces the application piston (4) to the right, causing the 
exhaust valve (5) to close the exhaust ports G and H, and the applica- 
tion valve (6) to uncover the port K; also causing the graduating 
spring on the stem (7) to be compressed. Air from the main reservoir 



44 



THE AIR-BRAKE 



is now free to flow from the chamber L through the port K and passage 
M to the brake-cylinders. 

In the movement just described, the ports N and in the slide- 
valve register with the ports J and P in the seat, and are connected 
by the cavity Q in the graduating valve. This connects the application 
chamber with the safety-valve, which, being adjusted to open at 53 
pounds, limits the cylinder pressure to this amount during a full 
service application. 

Service Lap. If the brake-pipe reduction is not sufficient to 



Brake* 
3-*^ Cylinder 



Main 
Reservoir & 



Double --^ 
Heading^ 




Application ^ ro 
Chamber Sifc* 

1 

/Application ^ ^ ^~ 

Chamber Is 



Brake - 
Pipe 

Safety 
Valve 



Fig. 32. Distributing Valve.— Emergency Position. 

cause a full service application, the air from the pressure chamber 
continues to discharge until the difference in pressure on the two sides 
of the piston (1) forces it and the graduating valve (2) toward the left. 
The frictional resistance of the slide-valve (3) prevents any further 
movement after the shoulder on the piston (1) strikes the right end 
of the slide-valve. In this position, all ports are closed, as in Fig. 31, 
and the valve is in service lap. Air continues to flow through the port 
K and the passage M into the brake-cylinders, until their pressure is 



THE AIR-BRAKE 45 

slightly in excess of that in the application chamber. This difference 
in pressure on the two sides of the piston (4), assisted by the graduat- 
ing spring on the stem (7), forces the piston (4) to the position shown 
in Fig. 31. This movement of the piston (4) results in application 
valve (6) closing the port K, but does not move the exhaust valve (5). 
The brake-cylinder pressure is then about the same as that in the 
application chamber. 

Emergency. When a sudden and heavy reduction of air-pressure 
is made in the brake-pipe, the piston (1) is forced to the right by the 
pressure in the pressure chamber until it strikes the gasket as shown 
in Fig. 32. This movement causes the slide-valve (3) to uncover 
the port J; and air from the pressure chamber passes quickly into the 
application chamber and becomes equalized. When the automatic 
brake-valve is placed in emergency position, the ports in the valve 
oonnect the equalizing reservoir to the application-chamber pipe. 
Air from the equalizing reservoir then passes into the application 
chamber, and, with that from the pressure chamber, equalizes at 
about 60 pounds. Air from the main reservoir enters the slide-valve 
chamber through the pipe L and the ports T and R, and passes into 
the pressure and application chambers. Air now escapes from the 
application chamber through the port J into the cavity S, through 
a small port into the port N, and thence out through the safety-valve. 
Air escapes through the safety-valve more rapidly than it can be 
supplied through the ports R and T, and thus prevents the pressure 
from becoming higher than is desired. 

In high-speed service, the feed-valve is set to maintain a brake- 
pipe pressure of 110 pounds instead of 70; and a main-reservoir 
pressure of 130 or 140 pounds is carried. The pressure in the applica- 
tion chamber, under these conditions, is increased to about 85 pounds; 
but air escapes through the cavity S and port N at about the same 
rate as in the high-speed reducing valve, until the pressure is only 
about 60 pounds. The pressure in the application chamber does not 
drop below about 60 pounds, because, under these conditions, air 
from the main reservoir is supplied through the ports R and T faster 
than it can escape through the restricted passages to the safety-valve. 

Emergency Lap. In emergency applications, the process above 
described continues until the brake-cylinder pressure slightly exceeds 
the pressure in the application chamber, when all parts move back 



46 



THE AIR-BRAKE 



to emergency lap position, as shown in Fig. 33. Release is accom- 
plished in the same manner as described under Fig. 29. 

In operating the locomotive brakes with the independent brake- 
valve, the action of the distributing valve is as follows : 

Independent Application. When making an application, the 
equalizing piston (1) occupies the same position as shown in Fig. 34. 
Air is admitted into the application chamber from the main reservoir 
through the reducing valve, at 45 pounds' pressure. This pressure 



Main 
Reservoir 




. Brake - 
fr^ Cylinder: 



BraKe- 
Pipe 

Safety 

Valve 



Double- 
Heading 
/-*■< 
Application 
Chamber 



Application^ S >*= 



Fig. 33. Distributing Valve.— Emergency Lap Position. 

also exists in the chamber E, and forces the piston (4) to the right, as 
shown. This movement causes the application valve (6) to uncover 
the port K f and air from the main reservoir passes through the passage 
M into the brake-cylinders. Air continues to flow into the brake- 
cylinders until their pressure and that in the chamber F slightly ex- 
ceeds that in the chamber E, when the piston (4) will be moved to 
the left, causing the application valve (6) to close the port. This 
position, shown in Fig. 35, is known as independent lap. 

It is easily seen that the action of the piston (4) will always main- 



THE AIR-BRAKE 



47 



tain about the same pressure in the brake-cylinders as exists in the 
application chamber. 

Independent Release. If the handle of the independent brake- 
valve is placed in release position, the air in the application chamber 
escapes directly to the atmosphere. This permits the brake-cylinder 
pressure in the chamber F to force the piston (4) to the left, causing 
the application valve (6) to close the port K, and the exhaust valve 
(5) to open the ports G and H, as shown in Fig. 29. Air is now free 
to escape from the brake-cylinders until the valve is placed in lap 



Brake* 
3-*^ Cylinder 



Main - 
Reservoir 6 




Application 
Chamber 



iwvvvvvv^^^vv^^^ ^^^v^xwvw^v 



Brake- 
Pipe 

Safety 
Valve 



Fig. 34. Independent Application of Distributing Valve. 

position or until the brake-cylinders are entirely exhausted. If the 
handle of the independent brake-valve is placed in lap position before 
all the air is exhausted from the brake-cylinders, the parts of the 
distributing valve will move to independent lap position, as shown in 
Fig. 35. In this way, the independent release may be graduated 
as desired. 

Safety-Valve. One of the essential parts of the distributing 
yalve is the safety-valve. The principle of its iction is shown in the 



48 



THE AIR-BRAKE 



section given in Fig. 36. Its construction is such as to cause t to 
close quickly with a pop action, which insures a firm sjating. The 
spring should be adjusted so that the valve will open at 53 pounds. 
This is accomplished by removing the cap nut (1) and screwing, up 
or down, an adjusting nut (2). 

Automatic Brake=Valve. The automatic brake-valve not only 
performs the functions of the standard engineer's valve commonly 



E5^N Brake- 
M b *^ Cylinder 



Main 
fteservoira 



Double--^, 
heading <l 




Application 



Application _J ^*" 
Chamber^ 



Brake - 
Pipe 

Safety 
Valve 



Fig. 35. Distributing Valve.— Independent Lap Position. 

installed on locomotives, but also those necessary to obtain all the 
desirable features of the distributing valve. 

Fig. 37 is taken from a photograph of this valve, with the handle 
in running position. 

Fig. 38 is a top view, showing the six positions of the brake-valve 
handle. 

Fig. 39 shows two views, the upper one being a section through 
the rotary-valve chamber, the rotary vah 1 < } md the 

lower one, a vertical section cf th f the top 

view of the rotary valve is shown on tlie lett. 



THE AIR-BRAKE 



49 



1 



The description of the operation of the valve in its different 
positions, will be given in the order in which it is most generally used. 

Charging or Release Position. 
In this position, air flows directly 
from the main-reservoir pipe, 
through the port A in the rotary 
valve and the port B in the valve- 
seat, into the brake-pipe. This 
quickly recharges the train-brake \v/ 
system and releases the train brakes, 
but does not reiease the locomotive 
brakes, if they are applied. The 
port C now registers with the port 
D, and permits main-reservoir pres- 
sure to enter the chamber E, and 
acts on the equalizing piston (2), 
forcing it downward and closing the 
discharge valve. In this position, 
the port F in the rotary valve (1) 
registers with the warning port G in 
the valve-seat, permitting a small 
amount of air to escape into the ex- 
haust cavity H. This serves to 
make enough noise to attract the 
engineer and notify him that the 
valve still remains in release position. 
A small groove in the face of the 
rotary valve connects the port F 
with the port I, and permits main- 
reservoir pressure to act on the ex- 
cess-pressure head of the pump- 
governor. If the handle of the 
automatic brake-valve is permitted 
to remain in this position too long, 
the brake-pipe and auxiliary reser- 
voirs would become charged to main-reservoir pressure. The handle 
should be moved to running or holding position before this occurs. 

Running Position. In running position, all the train and loco- 




Fig. 



36. Section of Safety- Valve of 
Distributing Valve. 



50 



THE AIR-BRAKE 



motive brakes are released, and the auxiliary reservoirs are charged. 

The ports J and B in the valve-seat are connected by the cavity K in 

the rotary valve; and air from the feed-valve pipe passes directly into 

the brake-pipe and re- 
charges the auxiliary res- 
ervoirs. The air in the 
brake-pipe will not attain 
a "pressure greater than 
that for which the feed- 
valve is set. The ports 
L and M in the valve-seat 
are connected by the cav- 
ity N in the rotary valve ; 
and the pressure on the 
equalizing piston (2) and 
in the equalizing reser- 
voir is the same as that 
in the brake-pipe. The 
port F in the rotary valve 

registers with the port 7 in the valve-seat, and permits main-reservoir 




Fig. 37. Automatic Brake- Valve. 




Fig. 38. Top View of Automatic Brake- Valve, Showing Six Positions of Handle. 

pressure to pass to the excess-pressure head of the pump-governor. 
The port in the rotary valve registers with the port P in the valve- 



THE AIR-BRAKE 



51 



Double-Heading Pipe, 



Feed-Valve > 
5&nd-Valve 



Application 
Chamber Pipe 




Main Reservoir 



Double Heading Pipe 



Application Chamber Pipe^ Equalizing Reservoir 



Fig. 39. Sectional Views of Automatic Brake- Valve. 
Upper view, a horizontal section through rotary- valve chamber, rotary valve removed. 
Plan view of rotary valve shown at left. Lower view, a vertical section through entire 
^alve. 



52 THE AIR-BRAKE 

seat, and connects the application-chamber pipe with the exhaust 
cavity H. 

Service Position. In this position, the brake-pipe pressure is 
gradually reduced and causes a service application. The port in 
the rotary valve registers with Q in the valve-seat, and permits air to 
discharge from the chamber E and the equalizing reservoir into the 
exhaust chamber H. The port Q is restricted, and causes a gradual 
discharge of air from the equalizing reservoir. As the pressure above 
the equalizing piston (2) is reduced, the brake-pipe pressure below 
forces the piston (2) upward, opening the discharge valve and exhaust- 
ing air from the brake-pipe into the atmosphere. When the pressure 
in the chamber E is reduced the required amount, the handle of the 
brake-valve is moved to lap position. Air will continue to exhaust 
from the brake-pipe through the discharge valve, until the pressure 
below the piston (2) is slightly less than that above. Equalizing 
piston (2) will then be forced downward, closing the equalizing valve. 
By this process, it will be seen that the reduction of the pressure in 
the equalizing reservoir determines that in the brake-pipe. 

Lap Position. This is the position the valve occupies while 
holding the brakes applied, to prevent loss of air from the main 
reservoir in case of a break-in-two, and when another engine in the 
train is handling the brakes. All ports are closed except the port in 
the rotary valve, which connects with the port R in the valve-seat. In 
double-heading, these ports connect with the application chamber in 
the distributing valve, and permit the air to exhaust into the atmos- 
phere when the automatic brakes are being released. 

Release Position. The action of the valve in this position has 
been described under charging or release. 

Holding Position. In this position, all train brakes are released, 
but the locomotive brakes are held applied. The only difference 
between the running and holding positions is that in the former the 
application chamber of the distributing valve is open to the atmos- 
phere, while in the latter it is not. 

Emergency Position. In this position, the port S in the rotary 
valve registers with the port M in the seat, and air discharges from 
the brake-pipe through the cavity T, into the exhaust chamber H, 
These ports are proportioned in such a manner that a large volume 
of air is suddenly discharged from the brake-pipe, causing all triple 






THE AIR-BRAKE 



53 




valves and the distributing valve to go to the emergency position. 
The cavity U in the rotary valve registers with L and P in the valve- 
seat, and permits the air from the equalizing reservoir to flow into the 
application chamber of the distributing valve. The ports C and V 
register and allow air from the main reservoir to flew to the sand 
valve, thus applying sand to the rails. 

Plug 3, shown in Fig. 39, is placed in the top of the case at a point 
to fix the level of an oil bath in which the rotary valve operates. 

Independent Brake=Valve. The independent brake-valve is of 
the rotary-valve type. Fig. 40 is 
taken from a photograph of the valve. 
The general construction of the valve 
is represented in Fig. 41. The lower 
view shows a vertical section of the 
entire valve, with a top view of the 
rotary valve on the right; while the 
upper one shows a horizontal section 
taken through the valve body with 

the rotary valve removed. All pipe Fig. 40. Independent Brake- Valve. 

connections, and the different positions of the handle, are shown. 

The action of the valve when placed in the different positions 
is as follows: 

Running Position, When the independent brake is not in use, 
the independent brake-valve should always be carried in this position. 
The ports A and B in the valve-seat are connected by the port C in 
the rotary valve (1). This establishes communication between the 
application chamber of the distributing valve and the port P (see 
Fig. 39) of the automatic brake-valve, so that the former can be 
operated by the latter. If the independent brakes are being operated 
with the automatic brake-valve in running position, they can be 
released by simply moving the independent brake-valve to running 
position, since in this position the air in the application chamber of 
the distributing valve can escape through the automatic brake-valve. 

Service Position. In this position, the ports D and B in the valve- 
seat are connected by the groove E in the rotary valve, allowing air 
to flow from the main reservoir to the application chamber. The 
air-supply from the main reservoir is reduced by the reducing valve 
to 45 pounds. This is the maximum pressure that can be obtained 



54 



THE AIR-BRAKE 



in the brake-cylinders when using the independent brake-valve. 

Lap Position. This position is used to hold the locomotive 
brakes after having been applied by using the independent brake- 
valve. All operating ports are closed. 

Release Position. In this position, the locomotive brakes will 
be released when the automatic brake-valve is not in running position. 

- Automatic Brake-Valve. 
Exhaust 



Application Chamber Pipe 
Quick Application. 




Fig. 41. Sectional Views of Independent Brake- Valve. 
Upper view, a horizontal section through valve body, rotary valve removed. Lower 
View, a vertical section through entire valve. Plan view of rotary valve shown at right. 

The port B in the valve-seat registers with the cavity F in the rotary 
valve, and air from the application chamber of the distributing valve 
exhausts into the atmosphere. 



THE AIR-BRAKE 



55 



If the valve is left in this position, it is impossible to operate the 
locomotive brakes by means of the automatic brake-valve. For this 
reason, the coil spring (3) is provided, which always returns the handle 
to running position as soon as the engineer lets go of it. The pur- 
pose of the oil plug (2) is the same as that described in connection 
with the automatic brake-valve. 

Reducing Valve. This is shown in Fig. 42, and is almost identi- 
cal with the feed-valve. The only difference in their construction 
is in the manner of adjustment. The principle of its action has 
already been described. 

Purn [/-Govern or. The pump-governor is shown in Fig. 43, 
with its different pipe connections named. When the automatic 
brake-valve is in release, running, or 
holding position, air from the main reser- 
voir flows through the automatic brake- 
valve into the chamber A below the 
diaphragm (1). Air from the feed-valve 
enters above the diaphragm (1), assist- 
ing the spring (2) to hold it down. 
Since the spring (2) is adjusted to a 
compression of 20 pounds, the diaphragm 
(1) will not be lifted until the main- 
reservoir pressure exceeds the feed-valve 
pipe pressure by mis amount. When 
this occurs, the diaphragm (1) is lifted, 
and the pin valve is opened. This 
permits main-reservoir pressure to act on the piston (3), forcing 
it downward and practically stopping the pump. Wlien the main- 
reservoir pressure in the chamber A becomes slightly reduced, the dia- 
phragm (1) is forced downward and the pin valve is closed. The air con- 
fined above the piston (3) escapes through the port B; the piston (3) is 
lifted by the action of the spring (4); and the pump starts working. 
When the automatic brake-valve is in any position other than release, 
running, or holding, the port connecting the automatic brake-valve 
with the chamber A is closed, and this governor head is cut out of 
action. The pump is then controlled by the other governor head, 
which is always connected with the main reservoir. Its action is 
similar to that just described. Both governor heads are adjusted by 




Fig. 42. Reducing Valve. 



56 



THE AIR-BRAKE 



screwing up or down on adjusting plugs (5). As both governor heads 
have a small vent port B from which air escapes whenever pressure 
is present above the piston (3), one of these should be plugged to 
avoid a waste of air. A small port in the valve (6) permits steam to 



FeedVxlv< 







Bcrile-F- 



— Pump 



Fig. 43. Vertical Section through Pump-Governor. 

enter the pump when it is cut out of action by the governor, which 
prevents freezing in cold climates. 

WESTINQHOUSE TYPE "K" TRIPLE VALVE 

The standard form of quick-action triple valve commonly used 
in freight and passenger service, has until recently proven very satis- 






THE AIR-BRAKE 



57 




factory. In the last few years, however, with heavier locomotives 
capaole of handling 100-car trains fitted with air-brake equipment, 
they have failed to meet all the requirements. Realizing the changed 
conditions and the importance of meeting them, the Westinghouse 
Company has recently perfected the "K" triple valve. 

Some of the undesirable features of the standard quick-action 
triple which the "K" triple overcomes, are as follows: 

(a) The failure of a portion of the. brakes in a long train to apply. 

(6) A complete release of the brakes at the forward end of the train 
before the brake-pipe pressure which has brought this about can reach the 
triple valves near the end of the train. This action permits the slack to run 
out hard, and creates excessive strains on the draft gears, often resulting in a 
break-in- two. 

(c) Overcharging the auxiliary reservoirs at the forward end of the train 
while releasing the brakes. The result of this action is a re-application of the 
forward brakes when the brake- valve handle is placed in running position. 

The outward appearance of the "K" triple valve, when attached 
to the auxiliary reservoir, is so much like the standard quick-action 



m 






Fig. 44. Westinghouse Type "K" Freight Triple Valve. 

triple that a thin web is cast on the top part of the body as a distin- 
guishing mark. The designating mark "K-l" or "K-2" is also cast 
on the side of the body. The "K" triple is made in two sizes — the 
"K-l" for use with the 8-inch freight-car brake-cylinder; and the 
"K-2," with the 10-inch freight-car brake-cylinder (see Fig. 44). 



58 



THE AIR-BRAKE 



This new valve embodies every feature possessed by the standard 
quick-action triple, and three additional ones — namely, the quick 
service, retarded release, and uniform recharge. It operates in perfect 
harmony with the standard triple, and often improves the action of 
the latter when the valves are mixed in the same train. The two 
types of valves have many parts in common and are interchangeable. 
The standard triple may be transformed into the "K" triple by pre- 
serving all of the old parts, save the body, slide-valve, bush, and 



£X3 



To Auxiliary 

Reservoir 



<2S55S23SS5SH5 



> 



a_ft_ftjLftjLa_ft<s 



iT9T9TTT 



^£ 



\mm\\^ 



_i_ 



To Brake - 
Cylinder 




From 
Brake-Pipe 



Fig. 45. Vertical Section through "K-2" Triple Valve, Showing General Arrangement of 

Values and Ports. 

graduating valve. This transformation can be done at a minimum 
cost when the valves are returned to the works for heavy repairs. 

A side view of the "K" triple valve, and the general arrangement 
of valves and ports, are shown in Figs. 45 and 46. Referring to Fig. 
45, those parts which are different and not found in the standard 
triple, are as follows: Valve Body (1), Slide-Valve (2), Graduating 
Valve (3), Retarding-Device Bracket (4), Retarding-Device Screw 
(5), Retarding-Device Washer (6), Retarding-Device Spring (7), 
Retarding-Device Stem Pin (8), and Graduating-V alve Spring (9). 



THE AIR-BRAKE 



59 



The quick-service feature gives a rapid serial operation of all 
brakes in service application. This is accomplished by using the 
principle of the standard triple in emergency applications — namely, 
discharging brake-pipe air into the brake-cylinder. That is, in service 
applications, some air from the brake-pipe passes into the brake- 
cylinder. The result is that the quick-service feature insures the 
operation of every brake, reduces the amount of air exhausted at the 
engineer's brake-valve and the possible loss of air due to flowing back 
through the feed-groove, and effects a saving of air. 

The retarded-release feature operates so as to give practically a 
simultaneous release of all brakes in the train. This is accomplished 
by automatically restricting the exhaust of air from the brake-cylinder 
in the forward portion of the train, and allowing the others to release 
freely. This retarded release is due to the increased pressure which 
exists in the forward end of the 
brake-pipe when the brake-valve is 
in release position, and affects about 
the first thirty cars in the train. 

The uniform recharge of the 
auxiliary reservoirs in the train is 
due to the fact that when the valve is 
in the retarded-release position, the 
ports connecting the brake-pipe with 
the auxiliary reservoir are automatic- 
ally restricted. In other words, as 
long as the exhaust from the brake- 



8-" 



Face View 
Graduating Valve, 



0C 



im 



s 



5 > 

"P 

N M r H 



Face View 



a« 



I 



'A if 

or, ;0' 

a::: 



-y p 



Top View 
Slide Valve. 



cylinder is retarded, the recharge is 
restricted. This feature not only 
prevents the overcharging of the 



^ G 



Slide Valve Bush. 



Fig. 46. Views of Graduating Valve, 

Slide-Valve, and Slide-Valve Bush 

of "K-2" Triple valve. 



but, by drawing less air from the 

brake-pipe, permits the increase in 

brake-pipe pressure to travel more 

rapidly to the rear cars, where it is most needed for releasing and 

recharging those brakes. 

By reference to Fig. 46, which shows views of the graduating 
valve, slide-valve, and slide-valve bush, it will be seen that the ports 
are arranged along a longitudinal center line, making it very difficult 



60 



THE AIR-BRAKE 



to follow the course of air through them with a sectional view such as 
is shown in Fig. 45. For this reason, diagrammatic views shown in 
Figs. 47, 48, 49, 50, 51, and 52 are used in explaining the operation 
of the valve. In order to assist to a clearer understanding of the 
valve, the notation used to distinguish ports, valves, etc., is the same 
in all figures. 

Referring to Fig. 45, the retarding-device brake (4) projects 
into the auxiliary reservoir; and its construction is such that free 
communication exists between the auxiliary reservoir and the cham- 
ber containing the slide-valve and the graduating valve. The grad- 
uating valve is of the slide-valve type, and moves over the top of the 
slide-valve, being carried along by the triple-valve piston. The 



fX-Pipe.^ 




'///////////////////i 



r^\*»n*n*P7Z. 



£122 



bvuuvv 



To Brake- 
Cylinder. 



Fig. 47. "K" Triple Valve in Full-Release and Charging Position. 

friction between the slide-valve and its seat prevents its movement 
until it is actuated by the triple- valve piston. 

The operation of the "K" triple valve is as follows : 
Full-Release and Charging Position. Fig. 47 shows the valve 
in this position. Air enters from the brake-pipe, and passes through 
the port A into the chamber B, through the ports C, into the cylinder 
D, through the feed-groove E, into the chamber F above the slide- 
valve, and finally passes into the auxiliary reservoir. . The feed-groove 
E is the same size as that used in the standard triple. In the "K-2" 
triple, the port H is added to the slide-valve, through which air enter- 
ing from the port G can feed into the auxiliary reservoir in order that 



THE AIR-BRAKE 



61 






a greater volume of air can be handled to supply the auxiliary reser- 
voir of a 10-inch brake-cylinder. The port H is not placed in the 
"K-l" triple. Brake-pipe pressure, entering by the port A, lifts the 
check-valve (10), passes through the ports G and H into the chamber 
F, and thence into the auxiliary reservoir. 

The process described above continues until the pressure in the 
auxiliary reservoir and brake-pipe become equal. The auxiliary 
reservoir is then said to be fully charged. 

Quick-Service Position. In making a service application of the 
brakes, air is slowly exhausted from the brake-pipe, and the pressure 
in the chamber D is reduced. When the difference in the auxiliary 
reservoir and brake-pipe pressures is sufficient to overcome the friction 




From 
Brake-Pipe. 




To Brake- 
Cylinder. 



Fig. 48. "K" Triple Valve in Quick-Service Position. 

of the piston (11) and the graduating valve (3), the piston moves 
to the left. As the piston (11) moves to the left, a shoulder on the 
right end of the piston strikes the right end of the slide-valve (2) and 
moves it to the left until the piston (11) strikes the end of the graduat- 
ing stem (13). The parts of the valve then occupy the position shown 
in Fig. 48. In this position, air flows from the auxiliary reservoir 
into the chamber F through the ports I and J, into the brake-cylinder. 
At the same time, the small amount of air contained in the cavity K 
passes through the ports G and L, the cavity M , the ports N and 0, 
around the emergency piston (12), into the brake-cylinder. When 
the pressure in the auxiliary reservoir drops below that in the brake- 



62 



THE AIR-BRAKE 



pipe, the check-valve (10) lifts, arid air passes from the brake-pipe 
through the ports mentioned above, into the brake-cylinder. The 
emergency piston (12) fits loosely in its cylinder and permits air to 
pass around it without pressing it downward. The pdrts G, L, N, 
and are proportioned so that there is no danger of any movement 
of the emergency piston (12). If this should occur, however, an 
emergency application would result. 

It is readily seen that the action just described will greatly reduce 
the brake-pipe reduction necessary at the brake-valve, since air is 
taken into the brake-cylinder from the brake-pipe; also, that a higher 
cylinder pressure will result than if no air from the brake-pipe passed 
into the brake-cylinder. 

Full-Service Position. In short trains, the volume of air in the 
brake-pipe is comparatively small. In service applications, aii 



y////////////////\ 






From 
Brake-Pipe. 




To Brake- 
Cylinder. 



Fig. 49. "K" Triple Valve in Full-Service Position. 

discharges so rapidly by the quick-service feature that an emergency 
would result were it not automatically prevented by the valve itself. 
In service applications, if the drop in brake-pipe pressure is more 
rapid than that in the auxiliary reservoir, then the valve takes the 
full-service position represented in Fig. 49. It will not, however, 
take the emergency position, because there is no sudden drop in the 
brake-pipe pressure. In the full-service position, the pressure behind 
the piston (11) is such that the graduating spring (14) is slightly com- 
pressed. This moves the slide-valve (2) to the left sufficiently to close 



THE AIR-BRAKE 



63 



the q dick-service port G, and brings the port / into full registration 
with the port J. In this position, no air can enter into the brake- 
cylinder through the port G; but since the ports I and J are fully 
open, air is free to pass from the auxiliary reservoir into the brake- 
cylinder. 

Lap Position. When the brake-pipe pressure has become con- 
stant after an application has been made, air continues to flow from 
the auxiliary reservoir through the ports I and J to the brake-cylinder, 
until the pressure in the chamber F becomes enough less than that 
in the chamber D to cause the piston (11) to move to the right. When 
the shoulder on the piston (11) strikes the left end of the slide-valve 
(2), it comes to rest on account of the frictional resistance of the slide- 




"'■ ) 






JUMHWIW/?/ 



-'//////////////A 



To Brake- 
Cylinder. 



1CT A 
V////////////M, 

Triple Valve in Lap Position. 

valve. In this position, all ports are closed and the valve is said to 
be lapped (see Fig. 50). 

Retarded-Release and Charging Position. It is a well-known 
fact that in a freight train fitted with standard triples, the cars nearest 
the engine will release first when the engineer places the brake -valve 
in release position. This is due, -first, to the friction of the air in the 
brake-pipe; and second, to the fact, that the auxiliary reservoirs of 
those brakes which release at the forward end begin to recharge 
taking air from the brake-pipe, which reduces the pressure -head. 
The retarded -release feature overcomes the second point mentioned 
by taking advantage of the first. The friction of the air in the brake- 
pipe causes the pressure to build up more rapidly in the chamber D 



64 



THE AIR-BRAKE 



of triples at the front end of the train, than it does in those at the rear. 
When this pressure in the chamber D increases sufficiently above that 
in the auxiliary reservoir to overcome the frictional resistance of the pis- 
ton, graduating valve, and slide-valve, all three parts move to the right 
until the piston strikes the retarding-device stem (8), which is held in 
position by the spring (7). The parts will then be in the position repre- 
sented in Fig. 47. If, however, the pressure in the chamber D builds up 
faster than the auxiliary reservoir can recharge (as is the case if the 
triple is near the head of the train), then the piston moves still farther 
to the right, compressing the retarding-device spring (7) until the 
parts occupy the position shown in Fig. 51. In this position, the back 



W///////////////. 



Brake-Pip£.^^^ 




To Brake 
Cylinder. 



Fig. 51. "K" Triple Valve in Retarded-Release Position. 

of the piston (11) is in contact with the slide-valve bush, and, acting 
as a valve, prevents any air from passing into the auxiliary reservoir 
through the feed-groove E ; but the port P now registers with the port 
G, permitting air to pass from the chamber A — lifting the check- valve 
(10) — through the ports G and P, into the auxiliary reservoir. By this 
latter route, the auxiliary reservoir is recharged only about half as 
fast as it would be if charged through the feed-groove E. As the 
pressure increases in the auxiliary reservoir and becomes nearly 
equal to that in the chamber D, the retarding-device spring (7) over- 
comes the friction of the piston, slide-valve, and graduating valve, 
and moves them to the left to the position shown in Fig. 47. After 
this, recharging continues through the feed-groove E until the pres- 
sures are equalized. In the retarded-release position, the exhaust 




THE AIR-BRAKE 



65 



cavity S connects the port J with the exhaust port T, and the air in 
the brake-cylinder is discharged into the atmosphere. The discharge 
is very slow, however, since the small extension of the cavity S (see 
Fig. 46) is over the port T. This is the retarded-release feature, 
and affects about the first thirty cars in the train. Finally, when the 
valve takes the position shown in Fig. 47, the cavity S completely 
covers the port T, and a free discharge of air from the brake-cylinder 
occurs. 

Emergency Position. This position is shown in Fig. 52. The 
operation of the "K" triple valve in emergency applications is the 



W//////////MA 



From 
Brake-Pipe. 




To Brake* 
G/ Under. 



Fig. 52. 



"K" Triple Valve in Emergency Position. 



same as that of the standard automatic quick-action triple. Quick 
action is produced by a sudden drop in the brake-pipe pressure. 

NEW YORK AIR=BRAKE SYSTEM 

The principle of action of the New York Air-Brake is precisely the 
same as that of the Westinghouse Air-Brake. The New York system 
is composed of the air-compressor, main reservoir, pump-governor, 
engineer's brake-valve, brake-pipe, triple valve, auxiliary reservoir, 
brake-cylinder, and pressure-retaining valve, which are the principal 
parts and are very similar to those used in the Westinghouse system. 
The only parts which need special explanation are the air-pump, 
engineer's brake-valve, and the triple valve. 

New York Air-Pump. The New York Air-Pump is a duplex 
pump, and is built in two sizes. The larger size is shown in section in 



66 



THE AIR-BRAKE 



Fig. 53. On the lower part are located the steam cylinders, each 
being 7 inches in diameter. The piston-rods connecting the steam 
pistons with the air pistons are made hollow for a portion of their 
length. This hollow portion provides a place for the stem which 
operates the steam valve. The action of the pump in compressing 



ifPipero 
Main Reservoi 




JS^Governor; 



4 Pipe Exhausf" 



Fig. 53. Section of New York Air-Pump. 

air is very similar to that of a compound steam engine, the air being 
compounded instead of steam. The entire valve-gear is very simple. 
The valves (1) and (2) controlling the action of the pistons are plain 
D slide-valves. The air-valves are simple check-valves. The opera- 
tion of the pump in compressing air is as follows: 



THE AIR-BRAKE 67 

Each air cylinder fills with free air at every stroke. The pistons 
of one side rest while those on the other side are in motion. The valve 
on one side controls the supply of steam to the opposite side. In the 
position of the pistons shown in Fig. 53, the piston (3) has completed 
its stroke, and has forced the air in the cylinder A through the air- 
valve (4) into the cylinder B at about 40 pounds' pressure. The plate 
on the piston (5) has come in contact with the shoulder on the valve- 
stem (6), and moved the steam valve (2) to the position shown. This 
opens the port E, and steam is permitted to act on the top of the piston 
(7), forcing it downward. The steam below the piston (7) passes out 
through the port F into the exhaust pipe. As the piston (7) descends, 
the piston (8) is pulled downward, forcing the partially compressed 
air in the cylinder B out through the air- valve (9) into the main reser- 
voir. 

As the piston (8) descends, air at atmospheric pressure enters 
through the air- valves (10) and (11) and fills the space above the piston 
(8). In the same way, the cylinder A above the piston (3) is also 
filled with air entering through the air-valve (10). When the piston 
(7) reaches the lower end of the cylinder C, the valve stem (14) is 
moved downward and causes the steam valve (1) to uncover the port 
G. Steam is now permitted to act below the piston (5), causing it to 
rise and force the air above the piston (3) through the valve (11), into 
the cylinder B above the piston (8). As the piston (5) ascends, the 
steam in the cylinder D passes through the port H and the cavity in 
the valve (1), into the exhaust pipe. Air entering through the air- 
valve (13) fills the cylinder A below the piston (3). When the piston 
(5) reaches its highest point, the head on valve-stem (6) engages with 
the plate on the piston (5), and lifts the steam valve (2) until the port 
F is uncovered. The piston (7), now being at the bottom of its stroke, 
is acted on by steam from the port F, and is forced upward, discharg- 
ing the air above the piston (8) through the air-valve (12) into the 
main reservoir. Air entering through the air-valves (13) and (4) 
fills the cylinder B below the piston (8). In this position, the plate 
on the piston (7) has lifted the valve-stem (14), causing the steam 
valve (1) to uncover the port H. Steam now acts on the top side 
of the piston (5) through the port H, forcing it downward and com- 
pleting the cycle. 

This type of air-pump is more efficient than the type represented 



68 



THE AIR-BRAKE 



by the nine and one-half inch Westinghouse air-pump, since the air 
cylinders are proportioned such that three measures of air are com- 
pressed for two measures of steam, whereas in the Westinghouse 
pump only two measures of air are compressed for two measures of 
steam. 

New York Engineer's Brake Valve. The New York engineer'^ 
brake-valve performs the same functions as the standard Westing- 
house engineer's brake-valve. It is illustrated in Figs. 54, 55, 56, 
and 57. Fig. 54 is a side view showing the different positions of the 




i-t. I To Gage 
-Red Hand - 
Main Reservoir 
Pressure. 




Fig. 54. Side View of New York Engineer's Brake- Valve, Showing 
Different Positions of Handle. 



handle. Fig. 55 shows a longitudinal section of the valve, a plan of 
the valve-seat, and the face of the slide-valve. Fig. 56 is a section 
through the feed-valve as seen from the rear. Fig. 57 is a section 
through the slide-valve as seen from the front. The action of the 
valve when in its different positions is described as follows : 

Running Position. Fig. 55 shows the position of the parts when 
the handle of the brake-valve is in running position. The main 
reservoir is in communication with the chamber A ; and the brake- 
pipe, with the chamber B. The chamber C, to the right of the piston 
(1), is connected to a small reservoir. When the handle is in running 



THE AIR-BRAKE 



69 



position, the discharge ports E, F, and G in the slide-valve (2) are 
closed; and air from the main reservoir flows from tne chamber A, 
lifting the feed-valve (3), passing through the port H (see Fig. 56), 
into the chamber B, and thence to the brake-pipe. 

Service Position. In making service applications, the handle of 
the brake-valve is placed in one of the service or graduating notches 




rr-n 



Fig. 55. Longitudinal Section of New York Engineer's Brake-Valve in Running Position, 
Showing also Plan of Valve-Seat (at top) and Face of Slide-Valve (at right) . 

illustrated in Fig. 54. Placing the handle in this position moves the 
slide-valve (2) to the right, uncovering the ports E and F } thus per- 
mitting brake-pipe air to escape from the chamber B to the atmos- 
phere through the passage D. Air continues to be discharged into 
the atmosphere until the pressure in the brake-pipe and chamber B 
is decreased sufficiently to permit the pressure in the chamber C 



70 



THE AIR-BRAKE 



b Small 
Reservoir 



(which is in communication with the small reservoir) to move the 
piston (1) to the left. This movement operates the small slide-valve 
(4), moving it to the right and closing the port E. The small reservoir 
mentioned above receives its supply of air from the chamber C, which, 
in turn, is supplied with air from the chamber B, entering through 
the ball check-valve (5). For light applications, the first notches are 
used : and for heavier ones, th last notches. Full-service application 
is obtained w T hen the handle is placed in the last service notch. 

Emergency Position. When the 
handle is placed in emergency posi- 
tion, the slide-valve (2) is moved to 
the right until direct communication 
is made between the chamber B and 
the exhaust passage D. In this po- 
sition, air flows from the chamber B 
through the port J (see Fig. 57) in 
the slide-valve, out through the port 
G, and into the exhaust passage D. 
Lap Position. In this position, 
all communication is closed between 
the main reservoir and the brake- 
pipe, and between the brake-pipe 
and the atmosphere. 

Release Position. When the han- 
dle is placed in release position, the 
slide-valve (2) is moved to the ex- 
treme left. In this position, the 
right end of the slide-valve (2) has uncovered the port K (see Fig. 55) 
in the valve-seat, and main-reservoir air flows from the chamber A 
into the chamber B and thence to the brake-pipe. At the same time, 
a small quantity of air in the chamber C and the small reservoir dis- 
charges through the ports I and J into the exhaust passage D; and 
brake-pipe pressure, acting on the piston (1), moves it to the position 
shown in Fig. 55, ready for the next service application. The vent 
valve (6) controls the passage I leading to the valve-seat. The handle 
of the brake-valve should not remain in this position too long, as there 
is danger of the auxiliary reservoirs becoming overcharged. 

If, after an application, the valve handle is placed in running 




Fig. 56. Section through Feed-Valve of 
New York Engineer's Brake- Valve, 
as Seen from Rear. 



THE AIR-BRAKE 



71 



position, the brakes will be released; but considerable time will be 
required, since the air must be supplied to the brake-pipe through the 
feed-valve (3). 

New York Quick-Action Triple Valve. Fig. 58 shows the New 
York triple valve in section. Its action is quite similar to that of the 
Westinghouse triple valve. It differs in its quick-action feature, 
however, in that, when an emergency application is made, no addi- 



TO 

GOVERNOR 



TO GAGE 
BLACK HAND 
Train Pipe 
Pressure 




TO GAGE 
RED HAND 

Main 
Reservoir 
Pressure 



TO 
MAIN 
RESERVOIR 

Fig. 57. Section through Slide- Valve of New York Engineer's Brake- Valve, 

as Seen from Front. 



tional brake-cylinder pressure is obtained above that secured in a full- 
service application. The action of the valve in service and emer- 
gency application is as follows : 

Charging and Release Position. The different parts of the valve 
are shown in this position in Fig. 58. Air from the brake-pipe enters 
the chamber A, passes through the ports B and C into the chamber D, 
through the feed-groove E into the chamber F, and into the auxiliary 
reservoir. Air continues to flow into the auxiliary reservoir until its 



72 



THE AIR-BRAKE 



pressure is the same as that in the brake-pipe. The head of the piston 
(1) is made so as to form a cylinder in which the piston (2) moves. 
Air at brake-pipe pressure enters the chamber G through the port H. 
If air-pressure exists in the brake-cylinder when the valve is in this 
position, it will flow out into the chamber I through the port J, the 
cavity K, and the port L, into the exhaust cavity M, to the atmosphere. 
In this position, air exhausts from the brake-cylinder until the brake 
is fully released. 

Service Position. When the engineer's brake-valve is placed in 
service position, air is exhausted from the brake-pipe, and the pressure 




Train Pipe -*■ 



Fig. 58. New York Quick-Action Triple Valve in Charging and Release Position. 

is gradually reduced. The reduced pressure on the left of the piston 
(1) causes auxiliary-reservoir pressure (on the right) to move it slowly 
to the left until it strikes the gasket (4). The motion, being slow, 
permits the air in the chamber G to exhaust through the port H. In 
this position, the piston (1) has moved the exhaust valve (3) to the left, 
closing the exhaust port J, and has caused the graduating valve (5) to 
uncover the port N. Air now flows from the auxiliary reservoir, 
through the port N, to the chamber /, into the brake-cylinder. 

Lap Position. If the brake-pipe reduction has not been sufficient 
to cause full equalization of the auxiliary-reservoir and brake-cylinder 
pressure, air will continue to flow from the auxiliary reservoir to the 
brake-cylinder until the pressure on the left of the piston (1) moves 
it toward the right. This movement of the piston (1) is stopped 



THE AIR-BRAKE 73 

when the left shoulder on the piston (1) strikes the left end of the 
exhaust valve (3). In this position, the port J is closed by the slide- 
valve (3), port N is closed by the graduating valve (5), and the valve 
is said to be lapped. 

Emergency Position. The piston (1) has the same movement in 
both service and emergency, positions. The port H is of such size 
that when the piston (1) moves slowly to the left, as in service applica- 
tions, the air in the chamber G is forced out without moving the piston 
(2) from the position shown. If an emergency application is desired, 
the handle of the engineer's brake-valve is moved at once to emergency 
position. This causes the brake-pipe pressure to drop very suddenly, 
and the piston (1) to move to the left so rapidly that the air in the 
chamber G cannot discharge through the port H fast enough to pre- 
vent the piston (2) from being disturbed. The result is that the 
piston (2) is moved to the left. This movement causes the valve (6) 
to be momentarily pushed from its seat by the stem of the piston (2). 
This allows air from the brake-pipe to enter the cavity 0, flow around 
the side to the chamber P, and escape to the atmosphere through the 
port Q. The air now in the chamber P forces the piston (7) to the 
right, which unseats the valve (8), and permits air from the auxiliary 
reservoir to flow through the port R, the valve (8), the chamber S, 
the check-valve (9), and the chamber T, into the chamber I, and 
thence to the brake-cylinder. As the last-mentioned passages are 
very large, full braking pressure is obtained instantaneously. While 
the action just described is going on, air from the chamber G is being 
discharged through the port H. When it is entirely exhausted, the 
spring (10) seats the valve (6), and all parts occupy positions as 
described under service position. 

FOUNDATION BRAKE-GEAR 

The foundation brake-gear includes all levers, rods, beams, pins, 
etc., which serve to transmit the braking force from the piston of the 
brake-cylinder to the brake-shoes. It is important that all longitudinal 
rods should be parallel with the center line of the car when the brakes 
are fully applied. The brake-beams should be hung in such a manner 
that they will always be the same distance above the rail, the reason 
being that this practice reduces the chance for flat wheels, since the' 
piston travel is not affected by the loading or unloading of the car. 



74 THE AIR-BRAKE 

The rods and levers should be designed so that they will move in the 
same direction when the brakes are applied by hand as when by air. 
The levers should stand approximately at right angles to the rods 
when the brakes are set. 

A number of different systems of rods and levers have been used 
by different railroad companies, with varying degrees of success. The 
systems adopted by the Master Car-Builders' Association are dia- 
grammatically shown in Fig. 59. The four cases shown represent 
two general systems — those where the brake-shoes are hung inside, be- 
tween the truck wheels, and those where they are hung outside. Freight- 

Hand Brake at One ELnd. 
Inside Hunq. 

CD ^ n U 




Outside Hunq. 

flD YT — TZD 



IZZL 




n 



Hand Brake at Both Ends. 
Inside Hunq. 

T ^— — ED F\ U 



O 



? 



o l 



Outside Hunq. 

tp T\ C^ 




0- 



Fig. 59. Foundation Brake-Gear Systems Adopted by Master Car-Builders' Association. 

cars are generally fitted with the brake-shoes hung inside, while 
passenger cars usually have the brake-shoes hung outside. In the 
first two systems (A and B), the brake can be applied by hand from 
only one end of the car; while in the other two systems (C and D) the 
brake can be operated by hand from either end. In applying the 
brake by hand in any case, the coil spring in the brake-cylinder offers 
no resistance, since the push rod has no pin connection to the piston 
rod. The piston-rod of the brake-cylinder is hollow. When the 
brake is operated by hand, the push rod slides outward in the hollow 
rod without moving the piston. A detailed description of the opera- 






THE AIR-BRAKE 



75 



tion of the four systems shown is 
not thought necessary. One or two 
points, however, might assist to a 
clearer understanding of them. The 
lower end of the lever (1) in the 
systems A and B is fixed at 0. The 
lower end of the lever (1) in the 
systems C and D is held by a stop 
at 0, and cannot move to the left, 
but is free to move to the right, when 
the brake is operated by hand from 
the right-hand end of the car. The 
lever (2) in all four systems has no 
fixed points. In all cases, the ar- 
rangement is such that no brake- 
shoe will press against its wheel 
with any great force until all brake- 
shoes are held firmly against their 
respective wheels, and all shoes press 
against the wheels with an equal 
force. 

Fig. 60, with all parts named, 
shows the application of the system 
A to a freight-car. No explanation 
is needed. 

Leverage. It is a well-known 
principle in Mechanics, that the 
greater the weight on a car wheel, 
the greater the brake-shoe pressure 
on that wheel necessary to cause it 
to slide on the track. For this 
reason, in designing the brake-rig- 
ging for a car, the light, or unloaded, 
weight of the car is the basis of all 
calculations. If the loaded weight 
of the car were used in calculating ( 
the levers, the proportions would be 
such that if the brakes were applied 



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Fig. 61. Illustrating Application of Principle of Moments to Levers in Brake Systems. 



THE AIR-BRAKE 77 

when the car was unloaded, the wheels would slide. In order to 

prevent any chance arising of having flat spots worn on the wheels, 

due to the wheels sliding on the track, the following percentages of 

light weights on the wheels are usually employed in determining the 

brake-shoe pressure: 

Passenger cars 90 per cent. 

Freight cars 70 per cent. 

Tenders 100 per cent. 

Locomotive drivers 75 per cent (of weight upon the 

drivers). 

Locomotive truck 75 per cent (of weight upon the 

truck). 
These percentages are sometimes changed to meet special conditions 
which arise. 

In calculating the brake- shoe pressure of any car, one must know 
three things: First, the diameter of the brake-cylinder and its maxi- 
mum pressure; second, the sizes and positions of all levers in the 
system; and third, a knowledge of the theorem of moments as used in 
Mechanics. 

The principle or theorem of moments may be stated thus : The 
product of the force applied at one pin and its perpendicular distance 
from the fulcrum pin, is equal to the product of the force delivered at the 
other pin and its perpendicular distance from the fulcrum pin. This 
principle has been applied tothe three different classes of levers; and 
the forces and distances have been worked out, and are shown in 
Fig. 61. The chief difficulty the beginner encounters is in locating 
the fulcrum pin. In A, B, and C (Fig. 61), the fulcrum pin is located 
at 0, the force applied is F, and the force delivered is W. In any case, 
if the pull F on the lever is known, the brake-shoe pressure W can 
be determined. 

Fig. 62 represents diagrammatically the scheme of levers and rods 
commonly used on freight-cars. All distances of rods from the center 
line of the car are taken when the levers are at right angles to it. The 
brake-cylinder is 8 inches in diameter, and has an area of about 50 
square inches. If the maximum brake-cylinder pressure in emergency 
applications is 60 pounds, the total pressure delivered to the push 
rod would be 50 X 60 = 3,000 pounds. This 3,000 pounds is trans- 
mitted to the lever E at the pin (1). The lever E is of the class shown 
in B (Fig. 61), and its fulcrum is at the pin (3). Applying the formula 
gives 4,500 pounds delivered at the pin (2). This 4,500 pounds is 



78 



THE AIR-BRAKE 




transmitted to the lever F, which is 
of the class shown in C (Fig. 61), 
and its fulcrum is at the pin (6). 
Applying the formula gives 1,500 
pounds delivered at the pin (4). This 
1,500 pounds is transmitted to the 
lever A, which is of the class shown 
in A (Fig. 61), and its fulcrum is at 
the pin (9). Applying the formula 
gives 6,000 pounds delivered to the 
brake-beam at the pin (8). In a 
similar manner the other brake-beam 
pressures can be determined. In 
the figure, the calculation has been 
carried through for both service and 
emergency applications. 

It is seen that 6,000 pounds is 
transmitted to the middle of each of 
the four brake-beams. Each brake- 
shoe will then receive a pressure of 
3,000 pounds. Since there are eight 
wheels, the total braking pressure 
will be 8 X 3,000 = 24,000 pounds. 
This total braking pressure must not 
exceed 70 per cent of the unloaded 
weight of the car. 

Automatic Slack= Adjuster. Full 
braking pressure will be secured as 
long as the maximum allowable 
brake-cylinder pressure can be 
maintained. Since the brake-cylin- 
der pressure depends upon the length 
of stroke of the piston, it follows 
that the stroke of the piston should 
be kept as nearly constant as possi- 
ble. The greater the stroke, the less 
the pressure. The stroke of the 
piston should be kept at about 8 



THE AIR-BRAKE 



79 



inches. As the brake-shoes and various connections wear, the 
stroke of the piston is increased, and the pressure with which the 
shoes are forced against the wheels is decreased. In order to com- 
pensate for this wear, some means must be provided for taking up the 




Fig. 63. Automatic Slack-Adjuster. 



slack. This is done in one of two ways, either by changing the fulcrum 
pin of the dead lever (see Fig. 60) or by using the automatic slack- 
adjuster. The first method of adjustment is the one most commonly 
used, and is necessarily very coarsely graded. The automatic slack- 




Fig. 64. Part Sectional View of Automatic Slack-Adjuster. 

adjuster, when used at all, is usually fitted to the passenger-car equip- 
ment. 

The automatic slack-adjuster, illustrated in Figs. 63 and 64, is 
manufactured by the Westinghouse Air-Brake Company. The 




80 



THE AIR-BRAKE 



purpose of the apparatus is to maintain a constant, predetermined 
piston travel. The brake-cylinder piston acts as a valve to control the 
admission and release of air to the pipe B through the port A. When- 
ever the stroke of the brake-cylinder piston is so great that the port 
A is passed by the piston, air from the cylinder enters the port A into 
the pipe B y and enters the cylinder C, which is shown in section in Fig. 
64. The air entering the small cylinder acts on the piston (1) forcing 
it to the left, compressing the spring (2), and causing the small pawl 
(3) to engage the ratchet wheel (4). When the brake is released, the 
brake-cylinder piston returns, and air in the small cylinder C escapes 
to the atmosphere through the pipe B and the port A, thus permitting 
the spring (2) to force the piston (1) to its normal position. In so 
doing, the pawl (3) turns the ratchet wheel (4) on the screw (5), and 




Fig. 65. Outside Equalized Driver-Brake for Locomotives. 

thereby draws the fulcrum end of the lever (6) slightly nearer the 
slack-adjuster cylinder C. Each operation of the piston (1), as just 
described, reduces the brake-cylinder piston travel about -gV of an 
inch. When the piston (1) is in its normal position, the outer end of 
the pawl (3) is lifted, permitting the screw (5) to be turned by hand. 

Locomotive-Driver Brakes. The brakes are applied to the 
drivers of a locomotive in two general ways — by the outside equalized 
system, as illustrated in Fig. 65; and by cams, as shown in Fig. 66. 
The former scheme has practically replaced the latter because of its 




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THE AIR-BRAKE 



being simpler in design and adjustment. The brake-cvlinders and 
auxiliary reservoirs used on locomotives are usually proportioned so 
that the pressure in the brake-cylinder will equalize at 50 pounds. 
In the system shown in Fig. 65, the levers are constructed so that each 
wheel receives the same braking pressure. If the brake-cylinder is 
14 inches in diameter and the cylinder pressure is 50 pounds, the 
pressure delivered at the pin A is about 7,650 pounds, while that on 
each wheel is 10,200 pounds. These values, of course, are different 
for different locomotives. The stroke of the piston is regulated by 
the adjusting mechanism at B. 

The action of the cam driver-brake is shown in Fig. 66. When 
air is admitted to the brake-cylinder, the piston is forced downward. 




Fig. 67. Locomotive-Truck Brake. 

This action pushes down the crosshead cams, which force the brake- 
shoes against the drivers. The piston travel is controlled by adjusting 
the cam nut on each cam. 

Locomotive-Truck Brake. In certain types of locomotives, a 
considerable proportion of the weight of the locomotive is carried on 
the truck. It follows, that in order to develop the full braking power 
of the locomotive, a well-designed truck brake should be provided. 
The type of brake shown in Fig. 67 is frequently used. It is fitted 



THE AIR-BRAKE 



83 



with an automatic slack-adjuster. This feature is not so important 
here as on the car equipment. 



WESTINGHOUSE TRAIN AIR-SIGNAL SYSTEM 

The train signal system is very essential in maintaining fast 
schedules with passenger trains. Its object is to furnish a means of 
communication between the trainmen and enginemen. It is made 
up of the following principal parts : 

1. A t-inch signal pipe, which extends throughout the length of the 
train, being connected between cars by flexible hose and suitable couplings. 

2. A reducing valve, which is located on the engine, and which feeds 
air from the main reservoir into the signal pipe at 40 pounds' pressure. 

3. A signal valve and whistle, located in the cab and connected to the 
signal pipe. 

4. A car discharge valve, located on each car, which is connected to the 
signal pipe. 

The action of the signal system is automatic. If an accident 
happens to the train, which breaks the signal pipe, the pressure in the 
signal pipe is reduced, and the 
whis^e in the cab blows a blast. 
The trainmen signal the enginemen 
by opening the card ischarge valve, 
which reduces the pressure in the 
signal pipe. This reduction of pres- 
sure in the signal pipe operates the 
signal valve in the cab, which admits 
air to the whistle. The operation 
of the various parts is as follows: 

Reducing Valve. A section 
through the reducing valve is shown 
in Fig. 68. This valve is located in 
a suitable place on the locomotive. 
Its purpose is to receive air from 
the main reservoir and feed it into 
the signal pipe, maintaining a pressure of 40 pounds. When no air 
is in the system, the parts occupy the position shown. When air is 
admitted from the main reservoir, it flows through the passage A and 
the supply valve (1), into the chamber B and out through the port C 
into the main signal pipe. When the air in the main signal pipe attains 




Fig. 68. Section through Reducing 
Valve in Westinghouse Air- 
Signal System. 



84 



THE AIR-BRAKE 



a pressure of 40 pounds, the pressure in the chamber B, acting on the 
piston (2), forces it downward, compressing the spring (3). This 
permits the spring (4) to close the supply valve (1). No more air can 
then enter the signal pipe until its pressure becomes reduced so that the 
spring (3) will force the piston (2) upward and lift the supply valve (1). 
Signal Valve. The signal valve controls the supply of air to the 
whistle. Whenever a reduction of air-pressure occurs in the signal 
pipe, the signal valve admits air to the whistle. A section of the valve 
is shown in Fig. 69. The two compartments A and B are divided by 



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-To Whistle 

Pig. 69. Section through Signal Valve in Westinghouse Air-Signal System. 

the diaphragm (1) to which is attached the stem (2). The stem (2) is 
milled triangular in section from the lower end to the peripheral 
groove (3). Above the groove (3), the stem (2) fits the bush (4) 
snugly. The lower end of the stem (2) acts as a valve on the seat (5). 
Air enters the signal valve from the signal pipe, through the passage C. 
It then passes through the small port D into the chamber A, and 
through the passage E, around the stem (2), into the chamber B. 
This charges the chambers A and B to signal-pipe pressure. A sudden 
reduction in signal-pipe pressure reduces the pressure in the chamber 
A; and the diaphragm (1), acted on by the pressure in the chamber 
B, rises, lifting the stem (2) and momentarily permitting air to pass 






THE AIR-BRAKE 



85 



from the signal pipe to the whistle. The resulting blast of the whistle 
is a signal to the enginemen. This same reduction of pressure in the 
signal pipe causes the reducing valve to recharge the system. The 
pressure in the chambers A and B equalizes quickly, and the lower end 
of the stem (2) returns to its seat. 

Cat Discharge Valve. The discharge valve is usually located 
outside the car, above the door, in such a position that the signal cord 
passing through the car can easily be 
fastened to the small lever of the valve. 




To Signal 
Pipe 




Fig. 70. Section through Car Discharge 
Valve in Westinghouse Air- 
Signal System. 



Fig. 71. Signal Whistle 
in Westinghouse Air- 
Signal System. 



Fig. 70 is a section of the valve. The vaive is connected to a 
branch pipe which extends from the signal pipe. The signal cord is 
connected to the eye in lever (1). Each pull in the signal cord causes 
the 1 ever (1) to open the check-valve (2), permitting air to escape 
from the signal pipe. This causes a reduction in the signal pipe, 
which, in turn, causes the whistle to blow as previously described. 
The spring (3) closes the valve (2) when the signal cord is not held. 
For the successful operation of the signal system, the signal pipe 
must be perfectly tight. Care must be exercised in using the car dis- 
charge valve, that sufficient time is permitted to elapse between succes- 
sive discharges. 



86 THE AIR-BRAKE 

SPECIAL INSTRUCTIONS IN USE AND CARE 
OF AIR=BRAKE EQUIPMENT 

Train Inspection. When a train is made up at a terminal, the 
air hose should all be coupled, and the angle-cocks all opened except 
the one at the rear end of the last car. The brake-pipe should then 
be charged to about 40 pounds, in order that the inspector may examine 
for leaks. When the brake-pipe has been fully charged, the engineer 
should apply the brake by making a light reduction in the brake-pipe, 
which should then be followed by a full-service application. He 
should note the time required in making these reductions, in order to 
be assured that all pistons are moved past the leakage groove when 
the train is out upon the road. The engineer, after making the full 
reduction, should leave his brake-valve in lap position until the 
inspector has examined the brake under every car. It should be the 
duty of the engineer to see that the brake equipment on the locomo- 
tive is in proper working order. 

Running Test. In passenger service, when a locomotive has been 
changed or a train made up, the engineer should make a running test 
within one mile of the station, as follows : A brake-pipe reduction of 
about 5 pounds should be made. If the brakes are felt to be apply- 
ing, and the time of the discharge is proportional to the number of 
cars in the train, the engineer will conclude that the brake is in proper 
working order. It is well, also, to make this test on approaching 
hazardous places. 

Service Applications. In making a service application of the 
brakes, the first reduction should be about 5 pounds on a train of 30 
cars or less, and about 7 pounds on a train exceeding 30 cars. This 
will insure the travel of all pistons beyond the leakage groove. Sub- 
sequent reductions of from two to three pounds can be made, to increase 
the braking power, if desired. A reduction of 25 to 30 pounds will 
make a full-service application. This should seldom be made, as it 
requires some time to recharge the system and release the brakes. 

In stopping a passenger train, two applications should be used; 
the first should reduce the speed of the train to about 8 miles an nom 
when the train is within two or three car lengths of the point at which 
the train is to be stopped. Moving the brake-valve handle to release 
position for only sufficient time to release all brakes, then returning it 



THE AIR-BRAKE 87 

to lap position, will make it possible for a second light application to 
stop the train. Just before all stops of passenger trains, except exact- 
position stops at water stations and coal chutes, the brakes should 
be released to avoid shocks to passengers. This release should be 
made on the last revolution of the drivers. If it should be made too 
soon, and the train keep on moving, the engineer's brake-valve should 
be moved to service position until the train stops 

In making stops of freight trains, the best practice is to shut oh 
the steam, and allow the slack to run in before applying the brakes. 
The stop should be made with one application of the brakes. After 
the first reduction is made, if there are any leaks in the brake-pipe, 
the braking force will be increased, and any subsequent reduction 
should be made less, in order to make up for these leaks. 

In stopping a long freight train at water stations and coal chutes, 
it is best to stop short of the place, cut off, and run up with the locomo- 
tive alone. 

On a freight train, where the locomotive is not equipped with the 
straight air-brake, the brakes should not be released when the speed 
of the train is 10 miles per hour or less. If this is done, the brakes in 
the front of the train will release, and, as the slack runs out, the train 
may part. If the locomotive is equipped with straight air, the train 
brakes can be released after the locomotive brakes are set, without 
danger of parting the train. This can also be accomplished by the 
use of the Westinghouse "E T" equipment. 

Emergency Applications. The emergency application should 
never be used, except in case of an emergency. If the necessity arises, 
an emergency application may be made after a service reduction of 
about 15 pounds. 

In case an emergency is caused by the train parting, hose burst- 
ing, or the conductor's valve being opened, the engineer should place 
his valve on lap, in order to save the main-reservoir air. 

Use of Sand. The use of sand increases the braking power of a 
train, and should be made in emergency stops. If sand is used in service 
stops, it should be applied some time before the brakes are applied, in 
order to have sand under the entire train. If, for any reason, the 
wheels should skid, do not apply the sand, as it will produce flat spots 
on the wheels. 

Pressure-Retaining Valve. In holding trains on grades, a part or 



88 THE AIR-BRAKE 

all of the retaining valves are set to hold 15 pounds in the brake- 
cylinder. If only part are set, those in the front of the train should be 
used. 

Backing Up Trains. In backing up freight trains, the train should 
be stopped by the hand-brakes on the leading end of the train, for the 
reason that if air were used, the brakes would apply on the cars near 
the engine and the leading cars might cause a break-in-two. 

In backing up a passenger train, where the train is controlled by 
a man on the leading car by means of an angle-cock, the engineer's 
valve should be in running position. This gives the man on the rear 
of the train full control of the brakes. As soon as the engineer feels 
the brake apply, he should place his valve on lap. 

Double=Heading. When two or more locomotives are coupled 
in the same train, the brakes are operated by the leading locomotive. 
The cut-out cocks in the brake-pipe just below the engineer's valve 
on all locomotives but the first, should be closed. The pumps on all 
engines should be kept running. 

Conductor's Brake- Valve. A conductor's brake-valve is located 
on each passenger car. The purpose of this valve is that the conductor 
may stop the train in case of emergency; if the engineer's brake-valve 
should fail to operate, he may signal the conductor to apply the brakes 
by opening the valve. 

Use of Angle-Cocks. In setting a car out of a train, first release 
the brakes, then close the angle-cock on both sides of the hose to 
be disconnected, and finally disconnect the hose by hand. Before 
leaving a car on the side track, the air-brakes should first be released 
by opening the release valve on the auxiliary reservoir; and if the car 
is on a grade, the hand-brake should be set. 

The angle-cock should not be opened on the head end of a train 
while the locomotive is detached. When connecting a locomotive 
to a train that is already charged with air, the angle-cock at the rear of 
the tender should be opened first, to allow the hose to become charged 
and thus prevent a slight reduction in the brake-pipe, which might set 
the brakes. All angle-cocks upon charged brake-pipes should be 
opened slowly. 

Cutting Out Brakes. If the brake equipment on any car is defec- 
tive, it may be cut out by closing the cut-out cock in the branch pipe 
leading from the brake-pipe to the triple valve. The release valve on 






THE AIR-BRAKE 89 

the auxiliary reservoir should be opened to discharge the air. Never 
more than three cars with their brakes cut out should be placed together 
in a train, on account of the emergency feature being unable to skip 
more than this number. 

Air-Pump. The air-pump should be run slowly with the drain- 
cocks open until the steam cylinder becomes warm and sufficient air- 
pressure has been attained to cushion the air, after which time the 
throttle may be fully opened. The lubricator should be in operation 
as soon as possible after starting, and the swab on the piston-rod 
should be kept well oiled. The air cylinder should receive oil each 
trip. Valve oil should be used, and it should be inserted through 
the oil-cup provided for that purpose, and not through the air 
strainer. 

Engineer's Brake- Valve. With the handle in running position, 
the main-reservoir pressure should be maintained at 90 pounds, and 
the brake-pipe at 70 pounds. This requires that the springs in the 
pump-governor and feed-valve must be carefully adjusted, and that 
no leaks exist between ports in the rotary valve. The rotary valve 
should be cleaned and oiled when necessary; and if leaks exist, the 
valve should be scraped to a fit. 

Triple Valve and Brake-Cylinders. These should receive an 
occasional cleaning and oiling, in order that they may be relied upon 
to fulfil their function. In cleaning the cylinder, special attention 
should be given to removing any deposit in the leakage groove. 
The walls of the cylinder should be coated with suitable oil or 
grease, and all bolts in the cylinder-head and follower should be kept 
tight. 

In cleaning the triple valve, a common practice is to place the 
removable parts in kerosene until the other parts and the brake- 
cylinder have been cleaned. The parts are then removed, cleaned, 
oiled, and replaced. Special care should be given to the slide-valve 
and its seat, and to the graduating valve. All lint should be removed 
before replacing the parts. The piston packing-ring should never be 
removed, except for renewing. A few drops of oil is all that is neces- 
sary for lubricating the entire triple valve. No oil should be permitted 
to get upon the gaskets or rubber-seated valve. The graduating- 
valve and check-valve springs should be examined, and, if necessary, 
renewed. 



90 THE AIR-BRAKE 

AIR=BRAKES AS APPLIED TO ELECTRIC CARS 

That electric street-cars and interurban cars should be equipped 
with reliable and efficient braking apparatus, is a well-established fact. 
It is emphasized by the frequent accidents which occur on roads 
where poorly constructed braking appliances are used. The modern 
electric car is several times heavier than cars used a decade ago, and 
speeds have increased remarkably, yet we frequently find cars fitted 
with braking apparatus but little better than that used in the days of 
the horse-car. Of recent years, the most progressive roads have 
given much attention to the construction of equipment, in order to 
insure the safety of their passengers, and, as a result, braking appliances 
have been greatly improved. 

The hand-brake was the first form of brake used on electric cars, 
and is still quite largely used. It is found to-day on most cars fitted 

with air-brakes, to be used in case 
of necessity. The early forms of 
the hand-brake consisted of a brake- 
staff located at either end of the car, 
having a chain connected to the 
lower end of the staff. As the han- 
dle is turned, the chain is wound 
up on the staff, and the resulting 
motion actuates the rods and levers 
which bring the brake-shoes in con- 
tact with the wheels. An improved 
form of brake-staff is that shown in 
Fig. 72. Here the winding drum 
takes the form of a spiral cam. In 
operation, the slack in the chain 
is quickly taken up and a very 
great braking pressure can be ob- 
tained. 

The first form of air-brake installed on electric cars was the 
Straight Air-Brake system. It is largely used to-day, as is also the 
Automatic Air-Brake system. The Straight Air-Brake system is 
usually found on trains of not more than two cars in length. Since 
electric roads do not at this time interchange cars to any great extent, 




Fig. 72. Hand-Brake for Electric Cars. 



THE AIR-BRAKE 



91 



there is no very great necessity for interchangeable air-brake apparatus. 
As a result, there are a number of different types of air-brake appara- 
tus found in use on electric cars. All operate more or less upon the 
same general principles. 

As the space allotted to this subject is limited, only one system 
will be described, namely — the Westinghouse system. This system 
is chosen, since it represents in a general way other systems in use on 
many roads. 

Westinghouse Straight Air-Brake. The action of the Westing- 
house Straight Air-Brake system for electric cars is the same as that 
already described for steam roads (see page 4). 

The system is composed of the following principal parts: 

1. An air-compressor, operated by an electric motor, to provide com- 
pressed air. 

2. A governor which automatically controls the action of the compressor, 
thereby maintaining the supply of compressed air at the proper pressure. 

3. A system of wiring, with the proper switches, fuse-boxes, etc., which 
connect the trolley current to the governor and compressor. 

4. A large reservoir in which compressed air is stored. 

5. A brake-cylinder and piston, the piston-rod of which is connected 
to the brake-rods in such a manner that when compressed air is admitted to the 
cylinder, and the piston moves outward, the brake-shoes are pressed against 
the tread of the wheels. 

6. An operating valve placed at either end of the car, .by means of which 
compressed air can be admitted from the reservoir into the brake-cylinder 
and exhausted from the brake-cylinder to the atmosphere. 

7. A system of piping connecting the above-mentioned parts, and, 
when trailers are used, including flexible hose and couplings and cut-out 
cocks. 

8. A safety-valve connected to the reservoir to prevent too great an 
accumulation of air should the governor fail to operate. 

9. A chime whistle connected to the air-supply, to be used as a warn- 
ing of approach. 

The general arrangement, names, and relative location of all 
parts, are shown diagrammatically in Fig. 73. 

Operating the Straight Air-Brake. The operating valve has 
notches placed upon it which mark the position of the handle for the 
various positions of the valve. This fact enables one to operate 
the brake with certainty the first time, but smooth and accurate stops 
can be made only after a little practice. Beginning from the right and 
going to the left, the different positions of the valve handle are as 
follows: Emergency position, service position, lap position, and 




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a 



o 

a 

Sh 

bo 
CIS 



bO 



THE AIR-BRAKE 



93 



release 'position (see Fig. 83). When the handle is in the lap position, 
as indicated by the deep notch, the main ports in the valve are closed, 
and compressed air cannot enter the brake-cylinder from the reservoir, 
and any compressed air which may be in the brake-cylinder cannot 
exhaust into the atmosphere. If the handle is now moved from this 
position to the extreme left, it will then occupy the release position. 
In this position, any air which may have been in the brake-cylinder 
will be exhausted into the atmosphere, and the brake will be released. 
This is the position the handle should occupy while running on a level 
track. If the handle is moved from the release position to the service 
position, air will flow very slowly from the reservoir into tke brake- 
cylinder, and service application results. If, however, the handle is 
moved from the release position to the extreme right (the emergency 
position), a large amount of air rushes from the reservoir into the 
brake-cylinder, and an emergency application is obtained. If the car 
is coasting down a grade, and the handle is moved to the service position 
for an instant and immediately returned to lap position, a small amount 
of air is admitted to the brake-cylinder and retained, thus holding the 
brakes applied. With a little experience, the proper amount of air 
can be admitted to the brake-cylinder in order that a constant speed 
may be maintained. If too much air is admitted into the brake- 
cylinder, a small portion can be exhausted by throwing the handle to 
release position for an instant, then back to lap position. 

The quickest stop possible is made by throwing the handle at 
once to the emergency position, giving to the wheels the greatest possi- 
ble braking pressure. The higher the speed, the greater the pressure 
that can be applied without danger of sliding the wheels. Thus it is 
seen that the quickest stop can be made by applying at once full brak- 
ing pressure (depending on the speed), and gradually releasing as the 
speed decreases. This method insures a smooth stop, as the rapid 
reduction of speed ajt the end of the stop, which throws passengers 
forward, is avoided. In making a service stop, about twenty-five 
or thirty pounds of air-pressure should be quickly admitted to the 
brake-cylinder, and gradually reduced as the speed decreases, retaining 
about ten pounds in the cylinder until the car stops. A little experi- 
ence is necessary in order to know just what pressures to use to be 
able to stop in a given distance. A succession of applications and 
release in stopping a car imparts a very disagreeable motion to the 



94 



THE AIR-BRAKE 



car, and is very wasteful of compressed air. In making emergency 
applications, the handle is thrown to the emergency position, and 
brake-cylinder pressure of, say, 60 pounds is obtained almost instantly. 
Sand should then be applied, and the handle be brought at once 10 the 




-Air Discharge 




trMlljllli^; 



Fig. 74. Motor-Driven Air-Compressor. 

lap position. The brake-cylinder pressure should then be released 
little by little as the speed drops. 

When the signal is received to go ahead, the handle should oe 
placed in release position before turning on the power. When 



THE AIR-BRAKE 



95 




descending a grade, the inexperienced man usually makes the mistake 
of applying the brake too hard at the start. It should be borne in 
mind that the car will not at once take the speed desired, and that 
some time is required for conditions to become constant. An easy 
application should first be made, and the handle held on lap until the 
car has sufficient time to feel the effect of the brake. If the speed of 
the car is still too high, let in a little more air, and repeat the operation 
as often as is necessary until off the grade. 

The following instructions are given by the Westinghouse Com- 
pany to motormen : 

"When leaving the car, always 
set up the hand-brake, as some one 
might tamper with the cut-out cocks. 
Before starting from the car-barn, be 
sure all cocks are properly set, and 
that there is a good supply of air in 
the reservoir. Insert the handle in its 
socket in the operating valve, and 
throw it around to emergency, then 
back to release, to see that it works 
freely. Try the air-brake both in 
service and in emergency, to make sure 
that it has not been left improperly 
connected, etc. After this trial, and 
as long as proper pressure is main- 
tained, the brake may be relied upon 
to perform its duty." 

Air-Compressor. The air- 
compressor may be either axle- 
driven or motor-driven. Since 
there are some objections raised 
against using the axle-driven 
compressor, and since the motor- 
driven compressor is more com- 
monly used, it is deemed advisa- 
ble to confine ourselves to the 
motor-driven compressor. Refer- 
ence will be made to Figs. 74, 75, and 76. All metal parts, such as 
pistons, rods, frames, etc., will be referred to as 1, 2, 3, etc., while all 
cavities and chambers will be called A, B, C, etc. 

The motor is of the series type, having an opening at the corn- 




Air Discharge 




Fig. 75. Motor-Driven Air -Compressor. 



96 



THE AIR-BRAKE 



mutator end which permits of ready access to the commutator. This 
opening is provided with a tight-fitting door which excludes all dirt, 
dust, and moisture. In the ends of the frame are fitted heads (1) 
and (2), which provide bearings for the ends of the armature. Each 
bearing is provided with two oil-rings which secure proper lubrication 
of the shaft. Oil-holes are provided for filling the oil-wells, and the 
location is such that there is no danger of flooding the interior of the 




Fig. 76. Air-Compressor Suspended in Cradle under Car. 

motor with oil. A passageway at the pinion end conducts any excess 
of gear-lubricating oil to the bottom of the gear case, thus assisting in 
preventing any flooding of the motor. Two of the poles of the motor 
are a part of the frame (3), and two are made up of soft laminated iron 
(4) bolted to the frame. The armature (5) is made up of soft-steel 
punchings which have accurately spaced slots in which are imbedded 
coils of uniform size. The brush-holders (6) are made of brass and 
are bolted to a cast-iron yoke with proper insulation. The brushes 
are carbon, and are held against the armature by coiled springs. 

The action of the compressor in compressing air is as follows: 
Air is drawn through the suction screen (7), lifts the check-valves (8), 
and passes through the ports A into the cylinders B. On the return 
stroke, the compressed air is forced out through the ports C, lifting the 
discharge valves (9), then passing into the chamber D, and finally 
into the discharge pipe E. The suction and discharge valves are 
made of steel, and are accessible by removing the caps (10) and (11), 
respectively. These valves do not have any coiled springs to seat 
them, but close by gravity. 



THE AIR-BRAKE 97 

The pistons (12) are accurately fitted with rings, and are made 
long so as to reduce the amount of wear. When repairing the pump, 
the rings should always be kept with the piston to which they belong. 
The wrist-pin (13) is made of steel, and works on a bronze bushing in 
the connecting rod. The crank end of the connecting rod is lined 
with babbitt which works on the crank, and has suitable means for 
adjustment. The center line of the cylinders is placed above that of 
the crank-shaft, in order that the angularity of the connecting rod 
may be reduced during the compression stroke. This reduces the 
vertical component of the thrust on the pistons, and thereby reduces 
the amount of wear on the cylinders. It should be remembered, how- 
ever, that the pump should always run with the compression part of 
the stroke on the upper half of the revolution. The crank-shaft is 
made of forged steel, and has two bronze bearings, one at either end, 
and a babbitt bearing in the middle. The crank-shaft bearings, 
wrist-pins, and crank-pins are lubricated by the splash system, from 
a bath of oil in the crank-case. The gear wheels (14) and (15) are of 
the herringbone type, and are lubricated from a bath of oil in the dust- 
proof gear-case. 

An air-compressor heats very rapidly when in operation, if no 
means are provided to conduct the heat away. For this reason, com- 
pressors which are designed for continuous service are always water- 
jacketed. Since compressors for electric-car service are used inter- 
mittently, they have time to cool, and a water-jacket is unnecessary. 
Experience has shown that such a compressor as just described, when 
compressing air at 100 pounds per square inch, should not run longer 
than 15 minutes at a time, and should then be permitted to cool at 
least fifteen minutes. This compressor is suspended under the car, 
in the position shown in Fig. 76, when in service. The method of 
suspension permits of its being readily removed for repairing. 

Pump-Governor. The location of the governor is shown in Fig. 
73. Its purpose is to start and stop the compressor in order to main- 
tain a predetermined pressure, by alternately making and breaking 
the circuit leading to the motor. A front view of the governor is 
shown in Fig. 77, and sections are shown in Figs. 78 and 79. The 
chamber A is in communication with the reservoir. The other side 
of the diaphragm (1) which forms one wall of the chamber A is open 
to the atmosphere. The diaphragm (1), therefore, is subjected to 



98 



THE AIR-BRAKE 



reservoir pressure on one side and atmospheric pressure and the regu- 
lating spring (2) on the other. The slide-valve (3) is connected to 
the diaphragm (1) in such a manner that any movement of the latter 
operates the former. When the maximum pressure is attained, the 




Fig. 77. Pump-Governor for Air-Compressor, Front View. 

regulating spring (2) is so adjusted that the diaphragm (1) is pressed 
downward. This moves the slide-valve (3) and uncovers the port B, 
which is in communication with the chamber C. The air-pressure 
now in the chamber C forces the piston (4) upward, thereby opening 
the switch in the motor circuit, and the motor stops. When the air- 



THE AIR-BRAKE 



99 



pressure in the reservoir drops slightly, and consequently the pressure 
above the diaphragm (1) is reduced, the regulating spring (2) forces 
the diaphragm upward, which also moves the slide-valve (3) and con- 
nects the port B with the exhaust port D. Air from the chamber C 




Fig. 78. Section through Pump-Governor for Air-Compressor. 

is now exhausted into the atmosphere; the piston (4) moves downward 
and closes the switch in the motor circuit ; and the pump starts. This 
action continues, and maintains the required pressure in the reservoir. 



100 



THE AIR-BRAKE 




Pig. 79. Pump-Governor for Air-Compressor, Side View. 



THE AIR-BRAKE 



101 



The mechanism on the upper part of the governor acts so as to cause 
the switch to open and close very rapidly, and thus avoids undue 
arcing. The pressure at which the governor cuts out the motor is 
controlled by adjusting the regulating spring (2) by means of the nuts 
(5). The governor may be located either under the car or in one end 
of the car. 

The electric apparatus above described is for direct current. 
Alternating-current motors and governors are being used to some 
extent, but have not yet come into very general use. 

Reservoir. The reservoir should have a sufficient capacity to 
supply air for three or four applications without reducing the pressure 
more than 15 pounds. It is conveniently located under the car, and 
its dimensions depend upon the size of the brake-cylinder used. It 
serves to collect moisture and oil, and prevents them from being carried 
further into the system. It should be drained frequently, as its capa- 
city for stored air will be reduced proportionally to the volume of water 
it contains. 

Brake-Cylinder. The brake-cylinder shown in Fig. 80 is of the 




N\\\\m\\\\mm 



BJjaasyaasagg^^^^^a^ssgm^^agssssgs^asss^^BB^m^g! 





imiii^mm^imm^ 



Fig. 80. Brake-Cylinder of Hollow-Rod Type. 

hollow-rod type. The piston is connected to the brake-rigging in such 
a way that it moves only when the power-brake is used. When the 
hand-brake is used, no movement of the piston occurs. The piston 
rod (1) is made hollow to receive the push rod. A leather packing- 
ring (2) is provided which prevents air from leaking around the piston. 
The leather packing-ring is held against the walls of the cylinder by 
means of the round spring expander (3). The cylinder-head (4) 
may be either plain or as shown. That shown is constructed to 



102 



THE AIR-BRAKE 



receive an automatic ^lack-adjuster (see page 79), which is sometimes 
used with the automatic system. 

When an application is made, air enters behind the piston and 
forces it outward, compressing the release spring (5). When the air is 
exhausted from the cylinder, the release spring (5) pushes the piston 
back to its normal position. Cylinder head (6) is constructed so as to 
provide a place for the coil spring when the piston is forced outward. 




Cylinder 



Fig. 81. Operating Valve of Westinghouse Straight Air-Brake 
View Showing Slide-Valve. 

The size of the cylinder depends on the design of the brake-rigging 
and on the weight of the car. The sizes commonly used are 8, 10, 
and 12 inches in diameter. 

Operating Valve. The purpose and operation of the operating 



THE AIR-BRAKE 



103 



valve has already been described (see page 91). The four positions 
of the valve are : Emergency, service, lap, and release. 

When in emergency position, full braking pressure is obtained 
almost instantaneously, and is used in avoiding collisions and making 
quick stops. In this position, direct communication is made between 
the reservoir and the brake-cylinder. The rail should always be 
sanded to avoid the possibility of 
slipping the wheel, which would 
result in making a poor stop and 
would probably cause a flat spot on 
the wheel. 

In service position, air enters 
the brake-cylinder pipe through a 
small port in the operating valve, 
and applies the brake very slowly. 

When in lap position, the ports 
in the operating valve are blocked, 
and air can flow neither to nor from 
the brake-cylinder. If the brake 
is applied, it will remain so until the 
valve is thrown to release position. 

If the valve is placed in release 
position, the cylinder and exhaust 
ports are connected, and only atmos- 
pheric pressure will remain in the 
cylinder. If the brake has been ap- 
plied, it will release when the valve 
is placed in this position. 

In describing the operating 
valve, reference will be made to 
Figs. 81, 82, and 83. The valve is 
cast in two parts — the base (1) and 
the head and body (2). On the top of the head is a double gauge (3) ; 
the red hand indicates the reservoir pressure ; and the black hand, the 
brake-cylinder pressure. Just below the gauge is a socket into which 
fits the operating handle (4) which is removable. In swinging from 
release position to emergency position, the handle turns through about 
130 degrees. The handle can be inserted and withdrawn only when 




Cylinder 



Reservoir 



Fig. 82. Operating Valve of Westing- 
house Straight Air-Brake, View Show- 
ing Reservoir Cavity. 



104 



THE AIR-BRAKE 



the valve is in lap position. When the handle is withdrawn, the latch 
(5) is thrown into position by a small spring, and the valve is perma- 
nently locked until the handle is again inserted. Just below the handle 
socket is a second one which contains a bolt (6) actuated by a spring. 
As the handle is turned, the head of the bolt (6) passes over notches 
which serve to indicate when the valve is in the proper position. 
Connected to the lower side of the socket is the stem (7) having a 



Top View 




Pressure 
Gauge 



Valve Seat 



Hiigiraenc 



K£ 




Fig. 83. Top View and Valve-Seat of Westinghouse Straight Air-Brake. 



pinion fitted to its lower end, which actuates the rack (8). The rack 
(8) is connected to and operates the slide-valve (9). The spring plate 
(10) does not act as a stop for the slide-valve (9), but is used only to 
assist in getting the valve in the proper position when assembling 
the parts. The slide-valve (9) moves between suitable guides (11) 
and (12). The chamber A is always in communication with the 
reservoir, and a port leads to the gauge above, which indicates the 
pressure. In the figure, the valve is shown in release position; air 
passes from the cylinder through the pipe B, the port C, the cavity D, 
the port E, thence to the exhaust pipe. When the valve is in emer- 
gency position, the right-hand edge of the slide-valve (9) registers 
with the left-hand edge of the port C. Air then passes from the 
chamber A, through the ports C and F, through the pipe B, to the 
brake-cylinder. In this position, the port E is blocked. In lap 
position, the right-hand portion of the slide-valve (9) covers the ports 
C and F, and the port E is blocked. The port G connects the brake- 
cylinder pipe with the gauge above, which indicates the cylinder 
pressure. 



THE AIR-BRAKE 



105 



Another form of this operating valve is sometimes used which has 
no gauge at the top to indicate the cylinder and reservoir pressures. 
The operation of the valve is the same as in the case of the one just 
described. 

The valve just described is sometimes used in a modified form 
as shown in Fig. 84. Here the operating handle and valve parts are 




Fig. 84. Type of Operating Valve with Handle and Valve Parts Separate. 
Westinghouse Straight Air-Brake System. 

separate, and the valve parts are bolted to the floor of the car. In 
operating this brake, the handle must be thrown in a way the reverse 
of that just described, but otherwise the operation of the valve is the 
same as previously given. 



106 



THE AIR-BRAKE 



Piping. Referring to Fig. 73, the sizes of the various pipes are 
as follows: 

The train-pipe connecting the brake-cylinder with the operating 
valve should be a standard J-inch pipe. If more than one trailer is 
used, a j-inch pipe should be used. 

The reservoir pipe, connecting the reservoir with the operating 
valve is a J-inch pipe. A f-inch pipe is better if it can be used con- 
veniently. 

The pump-governor and whistle connections are made with 

f-inch pipes. Wherever possible, long bends 
in pipes should be used, rather than a stand- 
ard elbow fitting. 

Safety-Valve. The safety-valve should be 
connected to the reservoir line leading to 
the controlling valve, at a point near the 
reservoir. Its operation may be understood 
by reference to Fig. 85. It can be set for 
any pressure by adjusting the regulating 
spring (1) by means of the nut (2). 

In an axle-driven compressor equipment, 
a slight change in the piping is necessary 
from that above described. Since the com- 
pressor is mounted on the truck, and has 
some movement relative to the car frame 
which carries the reservoir, flexible hose con- 
nections are necessary, to make connections 
to the reservoir and also to the compressor 
regulator. A small reservoir is also used 
which receives air from the compressor. 
This small reservoir is connected to the 
main reservoir by a pipe containing a regu- 
lating valve. The air attains a pressure of 
about 35 pounds in the small reservoir be- 
fore any air passes into the main reservoir. 
This 35 pounds' pressure in the small reser- 
voir is attained while the car runs about 100 yards, and is available for 
applying the brakes. This always insures air for operating the 
brakes if the car previously runs a short distance. With this ex- 




Fig. 85. Safety-Valve of 

Westinghouse Straight 

Air-Brake. 




?VD\ 



pq 



m 



108 



THE AIR-BRAKE 







to 



H 0< 



o 

to 



to 



ception, the piping is the 
same, and no further de- 
scription is necessary. 

If a car is fitted with 
a storage air-brake equip- 
ment, no compressor is 
installed in the car. The 
compressed air which is 
used for braking is car- 
ried on the car in large 
reservoirs. The general 
scheme of a storage air- 
brake equipment is 
shown in Fig. 86. Two 
large reservoirs connected 
by a one-inch pipe carry 
air at high pressure. 
These reservoirs deliver 
air through a reducing 
valve to a service reser- 
voir. The pressure in 
the service reservoir cor- 
responds to that in the 
reservoir previously de- 
scribed. Other than these 
parts just mentioned, the 
straight air-brake and 
the storage air-brake sys- 
tems are the same. 

Westinghouse Auto= 
matic Friction=Brake. 
The general scheme of 
this equipment is shown 
in Fig. 87, which gives 
the names of the princi- 
pal parts and their rel- 
ative location. The prin- 
ciple of its operation is 



THE AIR-BRAKE 109 

very different from that of the straight air-brake system. In the 
straight air-brake system, the brake-pipe is subjected to pressure 
only when an application is made. With the automatic system, air 
at 70 pounds' pressure per square inch is carried in the brake-pipe. 
The brake is applied by exhausting air from the brake-pipe, thus 
reducing its pressure; and it is released by restoring this pressure. 
It follows that any accident or operation which results in reducing the 
brake-pipe pressure will apply the brakes on all cars. This is not 
true, however, in case of the straight air-brake system. In the straight 
air-brake system, if any accident occurs to break or open the brake- 
pipe, the brake at once becomes inoperative. With the exception of 
compressed air being supplied by a motor-driven compressor, a gover- 
nor controlling the operation of this compressor, and a change in the 
form of the brake-valve, the system is almost identical with the Westing- 
house system already described for steam-operated roads. The 
descriptions of the operation of the automatic brake already given 
apply equally well to the automatic system for electric cars. The 
system is especially recommended for use on trains of more than two 
cars, where frequent stops are not required. 

The standard automatic air-brake system as used on steam roads 
to-day cannot be successfully operated on electric trains for street 
service composed of one car, for the following reasons: 

First. Applications of the brake are likely to follow in such rapid suc- 
cession that sufficient time would not be given to properly recharge the 
auxiliary or braking reservoir on each car. 

Second. A graduated release or gradual decreasing brake-cylinder 
pressure is absolutely necessary in electric-car work, in order to obtain a smooth 
stop. With the standard automatic equipment, release of the brake-cylinder 
pressure is complete, when once started. 

Third. A prompt response of the brakes when re-applied after a release, 
is very essential. This is not always possible in the standard automatic 
equipment, since the auxiliary reservoir is very slow in charging. 

To overcome these difficulties, there has been devised an auto- 
matic system for electric-car work, having quick-service, graduated- 
release, and quick-recharging features. This system is very important 
for a certain class of service, but will not be described. 

Train Air-Signal. As the size of electric cars and the length of 
trains increase, a signal system becomes more and more a necessity. 
That used to-day on steam roads has been fully described in preceding 
pages. Since the air-signal system used on electric cars is the same as 



110 



THE AIR-BRAKE 



that used on steam roads, it is unnecessary to repeat the description. 

Stopping a Car. The brake equipment of all electric cars is 

calculated with reference to the unloaded weight of the car, that is— 

the parts are so designed that there will be no danger of slipping the 

Y 




In stopping a car, the forces which 



100 200 300 4-00 50CT600 700 800 900 1000 X 

Distance in Feet Measured from Point 
of First Application of Brake 

Fig. 88. Diagram Showing Relation between Speed of Car and Distance in which Ston 
can be Made after Application of Brake. 

wheels when the car is unloaded, 
act to retard its motion are : 

The resistance of the atmosphere; 

The frictional resistance of the journals and track; and 

The resistance of the brake-shoes on the wheels. 

When the brake is applied, the car pitches forward on the front 
truck, and the weight on the rear truck is thereby decreased. If 
proper allowances have not been made in proportioning the brake- 



THE AIR-BRAKE 111 

levers, the rear wheels will probably slip on the track. If the wheels 
should slip, the distance required in which to bring the car to rest 
would probably be greater than that required had the wheels not 
slipped. In bringing a car to rest, the energy of translation of the entire 
car and the energy of rotation of all the wheels and motors must be 
absorbed by friction. To do this efficiently and safely in the shortest 
possible time, is the purpose of the modern brake systems. 

The average person who rides on street and interurban cars knows 
nothing as to the distance in which these cars can be stopped. "In 
what distance can a modern double-truck electric car be stopped ?" 
is a question which is frequently asked. In answer to this question, 
Fig. 88 has been prepared. A great many experiments have been 
made in stopping cars, with varying results. The chief factors which 
affect the results of such tests are the condition of the rail and the 
character of the material composing the brake-shoes. Fig. 88 shows 
graphically the relation between the distance required to stop a car 
and the speed (in miles per hour) at the instant the brake was applied. 
It represents the average result of a large number of experiments with 
a double-truck car fitted with brake equipment as described in the pre- 
ceding pages. With perfect conditions, the curve ABO would fall 
above that shown, while with very poor conditions, it would fall lower. 
The value of the diagram is made apparent by the following applica- 
tion: 

Example. Find the distance in which a double-truck electric car may 
be stopped if power is shut off and the brake applied while running at a speed 
of 30 miles per hour. 

Solution. Starting on the vertical line Y at 30 miles per hour, 
follow the horizontal line to the right until the curve A BO is reached 
at the point B. From the point B, follow the vertical line downward 
until the horizontal line X is reached at the point C. This point C 
indicates the distance in feet in which the car may be stopped, which in 
this instance is 4.40 feet. In the same way, the stopping distances may 
be determined for cars running at any speeds. 



INDEX 



INDEX 



A PAGE 

Air-brake 

as applied to electric cars 90 

early forms of 1 

foundation brake-gear 73 

interchangeable brake system 5 

introduction 1 

New York air-brake system 65 

special instructions in use and care of air-brake equipment 86 

Westinghouse 7 

Air-brake equipment, special instructions in use and care of 86 

air-pump . 89 

backing up trains 88 

conductor's brake-valve 88 

cutting out brakes 88 

double-heading 88 

emergency applications 87 

pressure-retaining valve 87 

running test 86 

service applications 86 

train inspection 86 

triple valve and brake-cylinders 89 

use of angle-cocks 88 

use of sand : 87 

Air-brakes as applied to electric cars 90 

air-compressor , 95 

brake-cylinder 101 

engineer's brake 89 

operating valve 102 

piping 106 

pump governor 97 

reservoir 101 

safety valve 106 

stopping car 110 

train air-signal 109 

Westinghouse automatic friction-brake 108 

Westinghouse straight air-brake 91 

Air-compressor 95 

Air-pump 89 

Air-pump governor 16 

Angle-cocks, use of 88 

Automatic brake-valve 48 

Automatic slack-adjuster 78 



2 INDEX 

]3 PAGE 

Brake-cylinder 101 

Brakes, cutting out 88 

C 

Conductor's brake-valve 88 

D 

Distributing valve 38 

E 
Engineer's brake-valve : 17, 89 

F 

Feed valve 22 

Foundation brake-gear 73 

automatic slack-adjuster 78 

leverage 75 

locomotive-driver brakes 80 

locomotive-truck brake 82 

II 

High-speed brake. . . 31 

I 

Independent brake-valve 53 

L 

Leverage 75 

Locomotive-driver brakes 80 

Locomotive-truck brake 82 

N 

New York air-brake system. . . . •. ' 65 

air-pump * 65 

engineer's brake-valve 68 

emergency position 70 

lap position 70 

release position 70 

running position 68 

service position 69 

quick-action triple valve 71 

charging and release position 71 

emergency position. 73 

lap position 72 

service position 72 

New York engineer's brake valve 68 

New York quick-action triple valve 71 

O 

Operating valve 102 



INDEX 3 

P PACK 

Piping 106 

Plain triple valve 27 

Pump-governor 55, 97 

Q 

Quick-action triple valve 25 

R 

Reducing valve 55 

S 

Safety-valve 106 

Sand, use of 87 

Slide valve 22 

T 

Train air-signal 109 

Train inspection 86 

V 

Valves 

automatic brake 48 

conductor's brake 88 

distributing 38 

engineer's brake. . 17 

engineer's brake-valve 89 

feed 22 

independent brake 53 

New York engineer's brake 68 

New York quick-action triple 71 

plain triple 27 

pressure-retaining 30, 87 

quick-action triple 25 

reducing 55 

slide - 22 

triple 89 

W 

Westinghouse air-brake system 7 

air-pump governor 16 

combined freight-car cylinder, reservoir, and triple valve. 29 

eight and one-half inch cross-compound 13 

engineer's brake-valve 17 

feed valve 22 

high-speed brake 31 

main reservoir 15 

nine and one-half inch air-pump 11 

operation of 11 

plain triple valve 27 

pressure retaining valve. 30 

quick-action triple valve. 25 

slide-valve 22 



4 INDEX 



PAGE 



Westinghouse automatic friction-brake 108 

Westinghouse "ET" locomotive brake equipment 33 

automatic brake-valve 48 

charging or release position 49 

emergency position 52 

holding position 52 

lap position 52 

release position 52 

running position 49 

service position 52 

distributing valve 38 

charging 41 

emergency 45 

emergency lap 45 

independent application 46 

independent release 47 

release 42 

safety-valve 47 

service 43 

service lap 44 

independent brake-valve 53 

lap position '. 54 

release position 54 

running position 53 

service position. 53 

manipulation 36 

pump governor 55 

reducing valve 55 

Westinghouse straight air-brake. 91 

Westinghouse train air-signal system 83 

car discharge valve 85 

reducing valve 83 

signal valve 84 

Westinghouse type "H" triple valve 56 

emergency position 65 

full-release and charging position 60 

full-service position 62 

lap position , 63 

quick-service position 61 

retarded-release and charging position 63 



The School Behind the Book 



THIS practical handbook is one of the representatives of 
the American School of Correspondence. It is the only 
kind of representative by which the School reaches the 
general public and extends its educational work. 

The American School of Correspondence is chartered, under 
the same laws as a State University, as an educational institution. 
Its instruction books, written especially to suit the needs of men 
seeking self improvement through correspondence work, are 
reserved for its students and for class use in educational institu- 
tions; many cf these texts are used in the class room work of the 
best resident schools in the country. 

However, in order that the large number of ambitious men, 
for whom class work and correspondence study are neither prac- 
tical nor advisable, may not be deprived of this valuable material, 
it is published by the School both in sets covering the several 
branches that it teaches, and in a series cf single Home Study 
volumes treating of specialized lines of practical knowledge. This 
book is a sample of the make-up of the Home Study volumes and 
the titles and authors are shown on the following page. By this 
method the School broadens its field of activity; and from these 
sales it derives an income to use in general educational work. 

The School's publications are clear and practical, and will 
be found ideal for reference and home reading. For those, how- 
ever, who desire more systematic study of the subjects in which 
they are particularly interested, the School advises a thorough, 
course by correspondence as the quickest and surest means of 
obtaining the practical knowledge desired. 

The School offers correspondence instruction in all branches 
of architecture, civil engineering, college preparatory, work, account- 
ing and business administration, drawing and design, electrical 
engineering, fire prevention and insurance, American law, mechan- 
ical, sanitary, and steam engineering, and textile manufacturing. 
It adapts its courses to the needs of the individual, by starting him 
where his previous education stopped, and giving him only such 
work as is necessary to fit him for the work he wants to do. 

On request the School will mail to any address a Bulletin 
•containing full information regarding its courses and methods. 
It employs no representative other than its own publications. 

AMERICAN SCHOOL OF CORRESPONDENCE 

CHICAGO, U. S. A. 



American School of Correspondence 

PRACTICAL HANDBOOKS FOR HOME STUDY 



OWING to a constant and increasing demand for 
low-priced single volumes covering the sub- 
jects treated in the courses and cyclopedias 
of the American School of Correspondence, a 
series of practical handbooks have been com- 
piled to be sold through the Book Stores all over the 
world. If any purchaser finds that his local dealer does 
not carry the particular title which interests him, he 
can order direct from the publisher, who will make 
shipment on receipt of price. If, after five days' exam- 
ination, the volume is found unsuited to his need, the 
purchaser may return it and his money will be promptly 
refunded. 



Partial List of Titles and Authors 

PRICE 

Alternating-Current Machinery William Esty $3.00 

Architectural Drawing and Lettering Bourne-von Hoist-Brown 1.50 

Bank Bookkeeping Charles A. Sweetland 1.00 

Boiler Accessories Walter S. Leland 1.00 

Bridge Engineering — Roof Trusses Frank O. Dufour 3.00 

Building and Flying an Aeroplane Charles B. Hay ward 1.00 

Building Superintendence Edward Nichols 1.50 

Business Management, Part I James B. Griffith 1.50 

Business Management, Part II Russell-Griffith 1.50 

Carpentry Gilbert Townsend 1 .50 

Care and Operation of Automobiles Morris A. Hall 1.00 

Commercial Law John A. Chamberlain 3.00 

Compressed Air Lucius I. Wightman 1.00 

Contracts and Specifications James C. Plant 1.00 

Corporation Accounts and the Voucher System, .James B. Griffith 1.00 

Cotton Spinning Charles C. Hedrick 3.00 

Department Store Accounts Charles A. Sweetland — 1.50 

Descriptive Astronomy Forest Ray Moulton 1.50 

Dynamo-Electric Machinery F. B. Crocker 1.50 

Electric Railways - Henry H. Norris 1.53 

The Electric Telegraph Thorn-Collins 1.00 



Partial List of Titles and Authors— Continued 

PRICE 

Electric Wiring and Lighting Knox-Shaad $1.00 

Estimating Edward Nichols 1.00 

Factory Accounts Hathaway-Griffith 1.50 

Forging John Lord Bacon 1.C0 

Foundry Work Wm. C. Stimpson 1.00 

Freehand and Perspective Drawing Everett-Lawrence 1.00 

The Gasoline Automobile Lougheed-Hall 2.00 

Gas Engines and Producers Marks-Wyer 1.00 

Heating and Ventilation Charles L. Hubbard 1.50 

Highway Construction Phillips-Byrne 1.00 

Hydraulic Engineering Turneaure-Black 3.00 

Insurance and Real Estate Accounts Charles A. Sweetland 1.50 

Knitting M . A. Metcalf 3.00 

Machine Design Charles L. Griffin 1.50 

Machine-Shop Work Frederick W. Turner 1.50 

Masonry and Reinforced Concrete Webb-Gibson 3.00 

Masonry Construction Phillips-Byrne 1.00 

Mechanical Drawing Ervin Kenison 1.00 

Modern American Homes H. V. von Hoist 3.00 

Motion Pictures David S. Hulfish 4. CO 

The Orders Bourne- von Hoist-Brown 3.00 

Pattern Making James Ritchey 1.00 

Plumbing Gray-Ball 1.50 

Power Stations and Transmission. Geo. C. Shaad 1.00 

Practical Aeronautics Chas. B. Hayward 3.50 

Practical Bookkeeping James B. Griffith 1.50 

Practical Lessons in Electricity Millikan- Knox- Crocker _ 1.50 

Reinforced Concrete Webb-Gibson 1.00 

Railroad Engineering Walter Loring Webb 3.C0 

Refrigeration M. W. Arrowwood 1.00 

Sewers and Drains A. Marston 1.00 

Sheet Metal Work William Neubecker 3.00 

Stair-Building and Steel Square Hodgson- Williams 1.00 

Steam Boilers Newell-Dow 1 .00 

Steam Engines L. V. Ludy 1.00 

Steam Turbines Walter S. Leland 1.00 

Steel Construction E. A. Tucker 1.50 

Strength of Materials Edward Rose Maurer 1.00 

Surveying Alfred E. Phillips 1.50 

Telephony Miller-McMeen 4.00 

Textile Chemistry and Dyeing =._ Louis A. Olney 3.00 

Textile Design Fenwick Umpleby 3.00 

Tool Making Edward R. Markham ___ 1.50 

Valve Gears and Indicators L. V. Ludy 1.00 

Water Supply Frederick E. Turneaure__ 1.00 

Weaving, H. William Nelson 3.00 

Wireless Telegraphy and Telephony Ashley-Hay ward 1.00 

Woolen and Worsted Finishing John F. Timmerman 3.00 

Woolen and Wo r sted Spinning Miles Collins 3.00 



J UN 23 1913 



LIBRARY OF CONGRESS 



021 218 372 6 



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